{"id":"CVE-2026-56814","revision":"8b896c777fb149059e077a5fc673a7c5","records":[{"revision":"8b896c777fb149059e077a5fc673a7c5","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-56814","aliases":[],"title":"Plug: multipart :length limit is not charged for part headers, enabling unbounded temp-file creation (denial of service)","description":"Plug.Parsers.MULTIPART, the multipart request-body parser used to handle file uploads and multipart forms, does not enforce its :length budget against all consumed resources, allowing an unauthenticated remote attacker to cause denial of service. The parser charges the :length limit only for part body bytes; part header bytes are never counted, and a part with an empty body costs zero.\n\nBecause every part whose Content-Disposition carries a non-empty filename creates a fresh temporary file (via Plug.Upload) and retains a Plug.Upload struct for the duration of the request, an attacker can send a single request composed of many empty-body file parts. Such a request stays well under the configured :length limit (8,000,000 bytes by default) while creating one temporary file per part, leading to inode and disk exhaustion and unbounded memory growth. Any application using Plug.Parsers with the :multipart parser is affected, and no authentication is required, only reachability of a multipart endpoint over HTTP.\n\nThis vulnerability is associated with program files lib/plug/parsers/multipart.ex and program routines Plug.Parsers.MULTIPART.parse_multipart/2, Plug.Parsers.MULTIPART.parse_multipart_headers/5, Plug.Parsers.MULTIPART.parse_multipart_body/4, and Plug.Parsers.MULTIPART.parse_multipart_file/4.\n\nThis issue affects plug: from 1.4.0-rc.0 before 1.16.6, from 1.17.0 before 1.17.4, from 1.18.0 before 1.18.5, from 1.19.1 before 1.19.5, and from 1.20.0 before 1.20.3.","state":0,"publishedAt":"2026-07-10T11:14:35.574+00:00","modifiedAt":"2026-09-24T21:31:15.419+00:00","affected":[{"ecosystem":"https://repo.hex.pm","name":"plug","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"collectionURL\": \"https://repo.hex.pm\",\n                    \"cpes\": [\n                        \"cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*\"\n                    ],\n                    \"defaultStatus\": \"unaffected\",\n                    \"modules\": [\n                        \"'Elixir.Plug.Parsers.MULTIPART'\"\n                    ],\n                    \"packageName\": \"plug\",\n                    \"packageURL\": \"pkg:hex/plug\",\n                    \"product\": \"plug\",\n                    \"programFiles\": [\n                        \"lib/plug/parsers/multipart.ex\"\n                    ],\n                    \"programRoutines\": [\n                        {\n                            \"name\": \"'Elixir.Plug.Parsers.MULTIPART':parse_multipart/2\"\n                        },\n                        {\n                            \"name\": \"'Elixir.Plug.Parsers.MULTIPART':parse_multipart_headers/5\"\n                        },\n                        {\n                            \"name\": \"'Elixir.Plug.Parsers.MULTIPART':parse_multipart_body/4\"\n                        },\n                        {\n                            \"name\": \"'Elixir.Plug.Parsers.MULTIPART':parse_multipart_file/4\"\n                        }\n                    ],\n                    \"repo\": \"https://github.com/elixir-plug/plug\",\n                    \"vendor\": \"elixir-plug\",\n                    \"versions\": [\n                        {\n                            \"lessThan\": \"1.16.6\",\n                            \"status\": \"affected\",\n                            \"version\": \"1.4.0-rc.0\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"lessThan\": \"1.17.4\",\n                            \"status\": \"affected\",\n                            \"version\": \"1.17.0\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"lessThan\": \"1.18.5\",\n                            \"status\": \"affected\",\n                            \"version\": \"1.18.0\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"lessThan\": \"1.19.5\",\n                            \"status\": \"affected\",\n                            \"version\": \"1.19.1\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"lessThan\": \"1.20.3\",\n                            \"status\": \"affected\",\n                            \"version\": \"1.20.0\",\n                            \"versionType\": \"semver\"\n                        }\n                    ]\n                }"},{"ecosystem":"https://github.com","name":"elixir-plug/plug","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"collectionURL\": \"https://github.com\",\n                    \"cpes\": [\n                        \"cpe:2.3:a:elixir-plug:plug:*:*:*:*:*:*:*:*\"\n                    ],\n                    \"defaultStatus\": \"unaffected\",\n                    \"modules\": [\n                        \"'Elixir.Plug.Parsers.MULTIPART'\"\n                    ],\n                    \"packageName\": \"elixir-plug/plug\",\n                    \"packageURL\": \"pkg:github/elixir-plug/plug\",\n                    \"product\": \"plug\",\n                    \"programFiles\": [\n                        \"lib/plug/parsers/multipart.ex\"\n                    ],\n                    \"programRoutines\": [\n                        {\n                            \"name\": \"'Elixir.Plug.Parsers.MULTIPART':parse_multipart/2\"\n                        },\n                        {\n                            \"name\": \"'Elixir.Plug.Parsers.MULTIPART':parse_multipart_headers/5\"\n                        },\n                        {\n                            \"name\": \"'Elixir.Plug.Parsers.MULTIPART':parse_multipart_body/4\"\n                        },\n                        {\n                            \"name\": \"'Elixir.Plug.Parsers.MULTIPART':parse_multipart_file/4\"\n                        }\n                    ],\n                    \"repo\": \"https://github.com/elixir-plug/plug\",\n                    \"vendor\": \"elixir-plug\",\n                    \"versions\": [\n                        {\n                            \"changes\": [\n                                {\n                                    \"at\": \"981597d3a4271ede64373c7a731702a42c500dd6\",\n                                    \"status\": \"unaffected\"\n                                },\n                                {\n                                    \"at\": \"56edca2ce35fe5589cd581644d8a4493fa5f484e\",\n                                    \"status\": \"unaffected\"\n                                },\n                                {\n                                    \"at\": \"0ee8afcc61466dc5f7a8f048d0632c899165b81f\",\n                                    \"status\": \"unaffected\"\n                                },\n                                {\n                                    \"at\": \"cae36053350e5215a4e0ca33cd130af9c5fc6364\",\n                                    \"status\": \"unaffected\"\n                                },\n                                {\n                                    \"at\": \"f7effaed811c00b5f5bf817936bfd9c5df27b7dc\",\n                                    \"status\": \"unaffected\"\n                                },\n                                {\n                                    \"at\": \"df97d3f17f808a9916a7700a701fb85314559d56\",\n                                    \"status\": \"unaffected\"\n                                }\n                            ],\n                            \"lessThan\": \"*\",\n                            \"status\": \"affected\",\n                            \"version\": \"c52b2f32c90bccd718202bafccb5f95594e30183\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","score":6.9,"severity":"MEDIUM"}],"references":["https://github.com/elixir-plug/plug/security/advisories/GHSA-95qv-c9g9-rm63","https://cna.erlef.org/cves/CVE-2026-56814.html","https://osv.dev/vulnerability/EEF-CVE-2026-56814","https://github.com/elixir-plug/plug/commit/c52b2f32c90bccd718202bafccb5f95594e30183","https://github.com/elixir-plug/plug/commit/981597d3a4271ede64373c7a731702a42c500dd6","https://github.com/elixir-plug/plug/commit/56edca2ce35fe5589cd581644d8a4493fa5f484e","https://github.com/elixir-plug/plug/commit/0ee8afcc61466dc5f7a8f048d0632c899165b81f","https://github.com/elixir-plug/plug/commit/cae36053350e5215a4e0ca33cd130af9c5fc6364","https://github.com/elixir-plug/plug/commit/f7effaed811c00b5f5bf817936bfd9c5df27b7dc","https://github.com/elixir-plug/plug/commit/df97d3f17f808a9916a7700a701fb85314559d56"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-56814","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-56814","identifiers":["CVE-2026-56814"]},"retained":false,"historicalAffected":[]}],"coverage":[]}