{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-97200",
        "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "state": "PUBLISHED",
        "assignerShortName": "EEF",
        "dateReserved": "2026-10-26T05:15:01.465Z",
        "datePublished": "2026-10-26T13:49:40.392Z",
        "dateUpdated": "2026-10-26T15:35:50.487Z"
    },
    "containers": {
        "cna": {
            "affected": [
                {
                    "collectionURL": "https://repo.hex.pm",
                    "cpes": [
                        "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*"
                    ],
                    "defaultStatus": "unaffected",
                    "modules": [
                        "hackney_conn",
                        "hackney"
                    ],
                    "packageName": "hackney",
                    "packageURL": "pkg:hex/hackney",
                    "product": "hackney",
                    "programFiles": [
                        "src/hackney_conn.erl",
                        "src/hackney.erl"
                    ],
                    "programRoutines": [
                        {
                            "name": "hackney_conn:read_full_body/2"
                        },
                        {
                            "name": "hackney_conn:maybe_decompress_body/2"
                        },
                        {
                            "name": "hackney_conn:decompress_gzip/1"
                        },
                        {
                            "name": "hackney_conn:decompress_deflate/1"
                        },
                        {
                            "name": "hackney:request/5"
                        },
                        {
                            "name": "hackney:body/1"
                        }
                    ],
                    "repo": "https://github.com/benoitc/hackney",
                    "vendor": "benoitc",
                    "versions": [
                        {
                            "lessThan": "4.9.0",
                            "status": "affected",
                            "version": "2.0.0-beta.1",
                            "versionType": "semver"
                        }
                    ]
                },
                {
                    "collectionURL": "https://github.com",
                    "cpes": [
                        "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*"
                    ],
                    "defaultStatus": "unaffected",
                    "modules": [
                        "hackney_conn",
                        "hackney"
                    ],
                    "packageName": "benoitc/hackney",
                    "packageURL": "pkg:github/benoitc/hackney",
                    "product": "hackney",
                    "programFiles": [
                        "src/hackney_conn.erl",
                        "src/hackney.erl"
                    ],
                    "programRoutines": [
                        {
                            "name": "hackney_conn:read_full_body/2"
                        },
                        {
                            "name": "hackney_conn:maybe_decompress_body/2"
                        },
                        {
                            "name": "hackney_conn:decompress_gzip/1"
                        },
                        {
                            "name": "hackney_conn:decompress_deflate/1"
                        },
                        {
                            "name": "hackney:request/5"
                        },
                        {
                            "name": "hackney:body/1"
                        }
                    ],
                    "repo": "https://github.com/benoitc/hackney",
                    "vendor": "benoitc",
                    "versions": [
                        {
                            "lessThan": "493e8bf83a391548e5101792276ab3fc428fa76c",
                            "status": "affected",
                            "version": "dc41b79339ca0c41e16d3f2dd17172bc2de855d6",
                            "versionType": "git"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "cpeMatch": [
                                {
                                    "criteria": "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*",
                                    "versionEndExcluding": "4.9.0",
                                    "versionStartIncluding": "2.0.0-beta.1",
                                    "vulnerable": true
                                }
                            ],
                            "negate": false,
                            "operator": "OR"
                        }
                    ],
                    "operator": "AND"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "type": "finder",
                    "value": "Martin Karrer"
                },
                {
                    "lang": "en",
                    "type": "finder",
                    "value": "Quinn Wilton"
                },
                {
                    "lang": "en",
                    "type": "reporter",
                    "value": "Quinn Wilton"
                },
                {
                    "lang": "en",
                    "type": "remediation developer",
                    "value": "Martin Karrer"
                },
                {
                    "lang": "en",
                    "type": "remediation developer",
                    "value": "Benoit Chesneau"
                },
                {
                    "lang": "en",
                    "type": "coordinator",
                    "value": "Jonatan Männchen / EEF"
                }
            ],
            "dateAssigned": "2026-10-26T09:42:31.000Z",
            "datePublic": "2026-10-25T00:00:00.000Z",
            "descriptions": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "<p>Allocation of Resources Without Limits or Throttling vulnerability in <code>hackney_conn</code> in benoitc hackney allows a malicious HTTP server to exhaust client memory via an oversized or highly compressed response body. <code>hackney:request/5</code> and <code>hackney:body/1</code> return the whole response body, and nothing bounds how much the connection process buffers. Any server the client requests can trigger it.</p>\n<p><code>hackney_conn:read_full_body/2</code> and the HTTP/2 and HTTP/3 accumulators append every chunk until the body ends. With <code>{auto_decompress, true}</code> the buffered body is then inflated in one step with <code>zlib:gunzip/1</code> or <code>zlib:inflate/2</code>, which return the whole output at once.</p>\n<p>This issue affects hackney: from 2.0.0-beta.1 before 4.9.0.</p>"
                        },
                        {
                            "base64": false,
                            "type": "text/markdown",
                            "value": "Allocation of Resources Without Limits or Throttling vulnerability in `hackney_conn` in benoitc hackney allows a malicious HTTP server to exhaust client memory via an oversized or highly compressed response body. `hackney:request/5` and `hackney:body/1` return the whole response body, and nothing bounds how much the connection process buffers. Any server the client requests can trigger it.\n\n`hackney_conn:read_full_body/2` and the HTTP/2 and HTTP/3 accumulators append every chunk until the body ends. With `{auto_decompress, true}` the buffered body is then inflated in one step with `zlib:gunzip/1` or `zlib:inflate/2`, which return the whole output at once.\n\nThis issue affects hackney: from 2.0.0-beta.1 before 4.9.0."
                        }
                    ],
                    "value": "Allocation of Resources Without Limits or Throttling vulnerability in hackney_conn in benoitc hackney allows a malicious HTTP server to exhaust client memory via an oversized or highly compressed response body. hackney:request/5 and hackney:body/1 return the whole response body, and nothing bounds how much the connection process buffers. Any server the client requests can trigger it.\n\nhackney_conn:read_full_body/2 and the HTTP/2 and HTTP/3 accumulators append every chunk until the body ends. With {auto_decompress, true} the buffered body is then inflated in one step with zlib:gunzip/1 or zlib:inflate/2, which return the whole output at once.\n\nThis issue affects hackney: from 2.0.0-beta.1 before 4.9.0."
                }
            ],
            "impacts": [
                {
                    "capecId": "CAPEC-130",
                    "descriptions": [
                        {
                            "lang": "en",
                            "supportingMedia": [
                                {
                                    "base64": false,
                                    "type": "text/html",
                                    "value": "<p>A server the client requests can make the client allocate memory proportional to the body it sends, or to its decompressed size, until the node runs out of memory.</p>"
                                },
                                {
                                    "base64": false,
                                    "type": "text/markdown",
                                    "value": "A server the client requests can make the client allocate memory proportional to the body it sends, or to its decompressed size, until the node runs out of memory."
                                }
                            ],
                            "value": "A server the client requests can make the client allocate memory proportional to the body it sends, or to its decompressed size, until the node runs out of memory."
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "Automatable": "NOT_DEFINED",
                        "Recovery": "NOT_DEFINED",
                        "Safety": "NOT_DEFINED",
                        "attackComplexity": "LOW",
                        "attackRequirements": "PRESENT",
                        "attackVector": "NETWORK",
                        "baseScore": 8.2,
                        "baseSeverity": "HIGH",
                        "privilegesRequired": "NONE",
                        "providerUrgency": "NOT_DEFINED",
                        "subAvailabilityImpact": "NONE",
                        "subConfidentialityImpact": "NONE",
                        "subIntegrityImpact": "NONE",
                        "userInteraction": "NONE",
                        "valueDensity": "NOT_DEFINED",
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
                        "version": "4.0",
                        "vulnAvailabilityImpact": "HIGH",
                        "vulnConfidentialityImpact": "NONE",
                        "vulnIntegrityImpact": "NONE",
                        "vulnerabilityResponseEffort": "NOT_DEFINED"
                    },
                    "format": "CVSS",
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "GENERAL"
                        }
                    ]
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-409",
                            "description": "CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)",
                            "lang": "en",
                            "type": "CWE"
                        }
                    ]
                },
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-770",
                            "description": "CWE-770 Allocation of Resources Without Limits or Throttling",
                            "lang": "en",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
                "shortName": "EEF",
                "dateUpdated": "2026-10-26T13:49:40.392Z"
            },
            "references": [
                {
                    "name": "hackney 4.9.0 release notes",
                    "tags": [
                        "vendor-advisory",
                        "related"
                    ],
                    "url": "https://github.com/benoitc/hackney/releases/tag/4.9.0"
                },
                {
                    "name": "EEF CNA record for CVE-2026-97200",
                    "tags": [
                        "related"
                    ],
                    "url": "https://cna.erlef.org/cves/CVE-2026-97200.html"
                },
                {
                    "name": "OSV record EEF-CVE-2026-97200",
                    "tags": [
                        "related"
                    ],
                    "url": "https://osv.dev/vulnerability/EEF-CVE-2026-97200"
                },
                {
                    "name": "Cap buffered response bodies with max_body_size and bound decompression (benoitc/hackney#980)",
                    "tags": [
                        "related"
                    ],
                    "url": "https://github.com/benoitc/hackney/pull/980"
                },
                {
                    "name": "Introducing commit dc41b79 in benoitc/hackney",
                    "tags": [
                        "related"
                    ],
                    "url": "https://github.com/benoitc/hackney/commit/dc41b79339ca0c41e16d3f2dd17172bc2de855d6"
                },
                {
                    "name": "Fix commit 493e8bf in benoitc/hackney",
                    "tags": [
                        "patch"
                    ],
                    "url": "https://github.com/benoitc/hackney/commit/493e8bf83a391548e5101792276ab3fc428fa76c"
                }
            ],
            "source": {
                "discovery": "EXTERNAL"
            },
            "title": "Unbounded response body buffering and decompression in hackney",
            "workarounds": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
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                            "type": "text/html",
                            "value": "<p>Leave <code>auto_decompress</code> disabled (the default). Without it <code>hackney_conn:maybe_decompress_body/2</code> never inflates the body, which closes the amplification half. The uncapped raw body read has no workaround.</p>"
                        },
                        {
                            "base64": false,
                            "type": "text/markdown",
                            "value": "Leave `auto_decompress` disabled (the default). Without it `hackney_conn:maybe_decompress_body/2` never inflates the body, which closes the amplification half. The uncapped raw body read has no workaround."
                        }
                    ],
                    "value": "Leave auto_decompress disabled (the default). Without it hackney_conn:maybe_decompress_body/2 never inflates the body, which closes the amplification half. The uncapped raw body read has no workaround."
                }
            ],
            "x_proofOfConcept": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "<ol>\n<li>Build a gzip stream whose inflated size is 1 GB from a reused 64 KB chunk of zero bytes (deflate with window bits 31, best compression). The stream is about 1 MB on the wire.</li>\n<li>Start a TCP listener on loopback that accepts one connection, reads the request, and answers <code>HTTP/1.1 200 OK</code> with <code>Content-Encoding: gzip</code>, a <code>Content-Length</code> matching the stream, <code>Connection: close</code>, and the stream as body.</li>\n<li>From a node running a vulnerable hackney, call <code>hackney:request(get, Url, [], &lt;&lt;&gt;&gt;, [{auto_decompress, true}, with_body])</code> against that listener.</li>\n<li>Observe the returned body of 1,048,576,000 bytes and the VM memory growing by about 1.8 GB for a 1,019,197 byte response. A larger stream, or an endless body without <code>auto_decompress</code>, drives the node out of memory.</li>\n</ol>"
                        },
                        {
                            "base64": false,
                            "type": "text/markdown",
                            "value": "1. Build a gzip stream whose inflated size is 1 GB from a reused 64 KB chunk of zero bytes (deflate with window bits 31, best compression). The stream is about 1 MB on the wire.\n2. Start a TCP listener on loopback that accepts one connection, reads the request, and answers `HTTP/1.1 200 OK` with `Content-Encoding: gzip`, a `Content-Length` matching the stream, `Connection: close`, and the stream as body.\n3. From a node running a vulnerable hackney, call `hackney:request(get, Url, [], <<>>, [{auto_decompress, true}, with_body])` against that listener.\n4. Observe the returned body of 1,048,576,000 bytes and the VM memory growing by about 1.8 GB for a 1,019,197 byte response. A larger stream, or an endless body without `auto_decompress`, drives the node out of memory."
                        }
                    ],
                    "value": "* Build a gzip stream whose inflated size is 1 GB from a reused 64 KB chunk of zero bytes (deflate with window bits 31, best compression). The stream is about 1 MB on the wire.\n* Start a TCP listener on loopback that accepts one connection, reads the request, and answers HTTP/1.1 200 OK with Content-Encoding: gzip, a Content-Length matching the stream, Connection: close, and the stream as body.\n* From a node running a vulnerable hackney, call hackney:request(get, Url, [], <<>>, [{auto_decompress, true}, with_body]) against that listener.\n* Observe the returned body of 1,048,576,000 bytes and the VM memory growing by about 1.8 GB for a 1,019,197 byte response. A larger stream, or an endless body without auto_decompress, drives the node out of memory."
                }
            ],
            "x_technicalAnalysis": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "<p><strong>1. Unbounded accumulation.</strong> <code>hackney:request/5</code> with a body, and <code>hackney:body/1</code> after <code>start_response/1</code>, read the response in <code>src/hackney_conn.erl</code> through <code>read_full_body/2</code>, which appends each chunk to a binary accumulator until the body ends. The HTTP/2 and HTTP/3 synchronous paths accumulate stream data the same way. No option caps the size.</p>\n<p><strong>2. One-step decompression.</strong> With <code>{auto_decompress, true}</code> hackney sends <code>Accept-Encoding: gzip, deflate</code>. Once the body is complete, <code>maybe_decompress_body/2</code> dispatches on <code>Content-Encoding</code> to <code>decompress_gzip/1</code> (<code>zlib:gunzip/1</code>) or <code>decompress_deflate/1</code> (<code>zlib:inflate/2</code>). Both return the whole output at once, so the inflated size is bounded only by the compression ratio. The report measured a 1 MB gzip body inflating to 1 GB on hackney 4.8.4.</p>"
                        },
                        {
                            "base64": false,
                            "type": "text/markdown",
                            "value": "**1. Unbounded accumulation.** `hackney:request/5` with a body, and `hackney:body/1` after `start_response/1`, read the response in `src/hackney_conn.erl` through `read_full_body/2`, which appends each chunk to a binary accumulator until the body ends. The HTTP/2 and HTTP/3 synchronous paths accumulate stream data the same way. No option caps the size.\n\n**2. One-step decompression.** With `{auto_decompress, true}` hackney sends `Accept-Encoding: gzip, deflate`. Once the body is complete, `maybe_decompress_body/2` dispatches on `Content-Encoding` to `decompress_gzip/1` (`zlib:gunzip/1`) or `decompress_deflate/1` (`zlib:inflate/2`). Both return the whole output at once, so the inflated size is bounded only by the compression ratio. The report measured a 1 MB gzip body inflating to 1 GB on hackney 4.8.4."
                        }
                    ],
                    "value": "1. Unbounded accumulation. hackney:request/5 with a body, and hackney:body/1 after start_response/1, read the response in src/hackney_conn.erl through read_full_body/2, which appends each chunk to a binary accumulator until the body ends. The HTTP/2 and HTTP/3 synchronous paths accumulate stream data the same way. No option caps the size.\n\n2. One-step decompression. With {auto_decompress, true} hackney sends Accept-Encoding: gzip, deflate. Once the body is complete, maybe_decompress_body/2 dispatches on Content-Encoding to decompress_gzip/1 (zlib:gunzip/1) or decompress_deflate/1 (zlib:inflate/2). Both return the whole output at once, so the inflated size is bounded only by the compression ratio. The report measured a 1 MB gzip body inflating to 1 GB on hackney 4.8.4."
                }
            ]
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "id": "CVE-2026-97200",
                                "role": "CISA Coordinator",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "yes"
                                    },
                                    {
                                        "Technical Impact": "partial"
                                    }
                                ],
                                "version": "2.0.3",
                                "timestamp": "2026-10-26T14:54:57.385457Z"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-10-26T15:35:50.487Z"
                }
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        ]
    }
}