{"id":"EUVD-2026-71661","revision":null,"records":[{"revision":"99881945b25f42f8966a9bcc5360a653","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-18540","aliases":[],"title":"undici vulnerable to downstream response splitting via retry interceptor","description":"undici's retry interceptor can append the body of a ranged retry response to bytes already delivered from an earlier partial response while still presenting the original response's status and headers. This happens when an upstream server delivers part of a body without a trustworthy resume checkpoint, for example a non-success response whose headers were already sent or a partial-content response with an unusable content range, then closes the connection and answers the resumed range request with more bytes. As a result the response body can be longer than the Content-Length that the application observes. An application that relays such a response to a downstream HTTP/1.1 peer without normalizing the framing can emit a body that exceeds the forwarded Content-Length, and the excess bytes can be interpreted as the start of a following response, which enables downstream response splitting or desynchronization. Exploitation requires an attacker-controlled upstream server and an application that forwards the response through a framing-sensitive path. This affects undici versions before 6.28.1, from 7.0.0 up to 7.29.1, and from 8.0.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.","state":0,"publishedAt":"2026-09-04T17:15:50.619+00:00","modifiedAt":"2026-09-04T17:50:13.682+00:00","affected":[{"ecosystem":"Vendor product","name":"undici","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"undici\",\n                    \"product\": \"undici\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"versions\": [\n                        {\n                            \"versionType\": \"semver\",\n                            \"status\": \"affected\",\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.28.1\"\n                        },\n                        {\n                            \"versionType\": \"semver\",\n                            \"status\": \"unaffected\",\n                            \"version\": \"6.28.1\"\n                        },\n                        {\n                            \"versionType\": \"semver\",\n                            \"status\": \"affected\",\n                            \"version\": \"7.0.0\",\n                            \"lessThan\": \"7.29.1\"\n                        },\n                        {\n                            \"versionType\": \"semver\",\n                            \"status\": \"unaffected\",\n                            \"version\": \"7.29.1\"\n                        },\n                        {\n                            \"versionType\": \"semver\",\n                            \"status\": \"affected\",\n                            \"version\": \"8.0.0\",\n                            \"lessThan\": \"8.10.2\"\n                        },\n                        {\n                            \"versionType\": \"semver\",\n                            \"status\": \"unaffected\",\n                            \"version\": \"8.10.2\"\n                        }\n                    ],\n                    \"packageURL\": \"pkg:npm/undici\"\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","score":3.7,"severity":"LOW"}],"references":["https://github.com/nodejs/undici/security/advisories/GHSA-r53p-7pc4-xj5r","https://cna.openjsf.org/security-advisories.html"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-18540","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-18540","identifiers":["CVE-2026-18540"]},"retained":false,"historicalAffected":[]},{"revision":"4a6a9bd2e0024806a3c2f7bafacd451c","observedAt":"2026-11-11T06:27:56.313+00:00","statement":{"source":"euvd","id":"EUVD-2026-71661","aliases":["CVE-2026-18540","GHSA-r53p-7pc4-xj5r"],"title":"undici's retry interceptor can append the body of a ranged retry response to bytes already delivered from an earlier partial response while still presenting the original response's status and headers. This happens when an upstream server de…","description":"undici's retry interceptor can append the body of a ranged retry response to bytes already delivered from an earlier partial response while still presenting the original response's status and headers. This happens when an upstream server delivers part of a body without a trustworthy resume checkpoint, for example a non-success response whose headers were already sent or a partial-content response with an unusable content range, then closes the connection and answers the resumed range request with more bytes. As a result the response body can be longer than the Content-Length that the application observes. An application that relays such a response to a downstream HTTP/1.1 peer without normalizing the framing can emit a body that exceeds the forwarded Content-Length, and the excess bytes can be interpreted as the start of a following response, which enables downstream response splitting or desynchronization. Exploitation requires an attacker-controlled upstream server and an application that forwards the response through a framing-sensitive path. This affects undici versions before 6.28.1, from 7.0.0 up to 7.29.1, and from 8.0.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","score":3.7,"severity":null}],"references":["https://github.com/nodejs/undici/security/advisories/GHSA-r53p-7pc4-xj5r","https://cna.openjsf.org/security-advisories.html"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-71661","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Sep 4, 2026, 5:15:50 PM","dateUpdated":"Sep 4, 2026, 5:50:13 PM"},"relatedAdvisories":[{"id":"RHSA-2026:71017","title":"Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update","vulnerabilityIds":["CVE-2026-18540","CVE-2026-19534","CVE-2026-85024"]},{"id":"RHSA-2026:66008","title":"Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update","vulnerabilityIds":["CVE-2026-14199","CVE-2026-18149","CVE-2026-18540","CVE-2026-19197","CVE-2026-19534","CVE-2026-28378","CVE-2026-84890","CVE-2026-84933","CVE-2026-84947","CVE-2026-84961","CVE-2026-85008","CVE-2026-85014"]},{"id":"WID-SEC-W-2026-3596","title":"IBM App Connect Enterprise: Mehrere Schwachstellen","vulnerabilityIds":["CVE-2022-35948","CVE-2026-13149","CVE-2026-14257","CVE-2026-15157","CVE-2026-1527","CVE-2026-16728","CVE-2026-16729","CVE-2026-18149","CVE-2026-18540","CVE-2026-19534","CVE-2026-2391","CVE-2026-45820","CVE-2026-54272","CVE-2026-63670","CVE-2026-67213","CVE-2026-67214","CVE-2026-69152","CVE-2026-69192","CVE-2026-69198","CVE-2026-73566","CVE-2026-73646","CVE-2026-77037","CVE-2026-77063","CVE-2026-77078","CVE-2026-82333","CVE-2026-82417","CVE-2026-82562","CVE-2026-83605","CVE-2026-83606","CVE-2026-83607","CVE-2026-83608","CVE-2026-83609","CVE-2026-83610","CVE-2026-83611","CVE-2026-83612","CVE-2026-83613","CVE-2026-83614","CVE-2026-83615","CVE-2026-83616","CVE-2026-83618","CVE-2026-83619","CVE-2026-84292","CVE-2026-84371","CVE-2026-84375","CVE-2026-84890","CVE-2026-84933","CVE-2026-84947","CVE-2026-84961","CVE-2026-85008","CVE-2026-85014","CVE-2026-85024","CVE-2026-85152"]},{"id":"RHSA-2026:66605","title":"Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update","vulnerabilityIds":["CVE-2026-18540","CVE-2026-19534","CVE-2026-84961","CVE-2026-85024"]},{"id":"msrc_CVE-2026-18540","title":"undici vulnerable to downstream response splitting via retry interceptor","vulnerabilityIds":["CVE-2026-18540"]}],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-71661","identifiers":["EUVD-2026-71661","CVE-2026-18540","GHSA-r53p-7pc4-xj5r"]},"retained":false,"historicalAffected":[]},{"revision":"a21de45df60a4fee956f8b1f8fee3d3f","observedAt":"2026-10-25T05:17:25.909+00:00","statement":{"source":"nvd","id":"CVE-2026-18540","aliases":[],"title":"undici's retry interceptor can append the body of a ranged retry response to bytes already delivered from an earlier partial response while still presenting the original response's status and headers. This happens when an upstream server de…","description":"undici's retry interceptor can append the body of a ranged retry response to bytes already delivered from an earlier partial response while still presenting the original response's status and headers. This happens when an upstream server delivers part of a body without a trustworthy resume checkpoint, for example a non-success response whose headers were already sent or a partial-content response with an unusable content range, then closes the connection and answers the resumed range request with more bytes. As a result the response body can be longer than the Content-Length that the application observes. An application that relays such a response to a downstream HTTP/1.1 peer without normalizing the framing can emit a body that exceeds the forwarded Content-Length, and the excess bytes can be interpreted as the start of a following response, which enables downstream response splitting or desynchronization. Exploitation requires an attacker-controlled upstream server and an application that forwards the response through a framing-sensitive path. This affects undici versions before 6.28.1, from 7.0.0 up to 7.29.1, and from 8.0.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.","state":0,"publishedAt":"2026-09-04T18:17:50.02+00:00","modifiedAt":"2026-09-16T20:41:17.627+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · ce714d77-add3-4f53-aff5-83d477b104bb · Secondary","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","score":3.7,"severity":"LOW"}],"references":["https://cna.openjsf.org/security-advisories.html","https://github.com/nodejs/undici/security/advisories/GHSA-r53p-7pc4-xj5r"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-18540","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Analyzed","weaknesses":["CWE-444"],"productCriteria":["cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*"],"sourceDates":{"published":"2026-09-04T18:17:50.020","lastModified":"2026-09-16T20:41:17.627"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-18540","identifiers":["CVE-2026-18540"]},"retained":false,"historicalAffected":[]},{"revision":"a8ab67f572214576b9245b33a92167a9","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-r53p-7pc4-xj5r","aliases":["CVE-2026-18540"],"title":"undici vulnerable to downstream response splitting via retry interceptor","description":"### Impact\n\nUndici's `interceptors.retry()` can resume a request after a partial response and append the resumed bytes to an already partially delivered body, while the application still receives the original response's status and headers. When that response carried a `Content-Length`, the application can receive a longer body. Applications that forward Undici's status, headers, and body downstream without recalculating framing, for example proxy or gateway applications, may emit a response whose body exceeds the forwarded `Content-Length`, and the excess bytes can be read as the start of a subsequent HTTP response (downstream response splitting or desynchronization).\n\nFor example, a `404 Not Found` with `Content-Length: 2` that sends one byte then closes can be resumed with an open-ended `Range` request, and the resumed `206 Partial Content` bytes are appended, so the application receives more than two body bytes while still seeing `Content-Length: 2`. The bug requires `interceptors.retry()` enabled, an attacker-controlled or faulty upstream, and a downstream forwarder that does not recalculate `Content-Length`.\n\n### Patches\n\nPatched in undici v6.28.1, v7.29.1, and v8.10.2. Upgrade to one of these or later.\n\n### Workarounds\n\n- Disable `interceptors.retry()` for untrusted upstreams, or set `maxRetries: 0`.\n- Remove or recalculate `Content-Length` before forwarding a response body assembled by Undici.","state":0,"publishedAt":"2026-09-29T18:22:07+00:00","modifiedAt":"2026-09-29T18:30:41.1545321+00:00","affected":[{"ecosystem":"npm","name":"undici","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"6.28.1"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"npm","name":"undici","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"7.0.0"},{"kind":"fixed","version":"7.29.1"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"npm","name":"undici","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"8.0.0"},{"kind":"fixed","version":"8.10.2"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"LOW"}],"references":["https://github.com/nodejs/undici/security/advisories/GHSA-r53p-7pc4-xj5r","https://nvd.nist.gov/vuln/detail/CVE-2026-18540","https://github.com/nodejs/undici/commit/0160a719063fb0a77f4fdf9500b9166b91e14329","https://github.com/nodejs/undici/commit/cd8af90b38ae33c2838d54a2d629774122effe95","https://github.com/nodejs/undici/commit/ce31bc824b578008faae5d3350da66c1b5f71548","https://hackerone.com/reports/3900104","https://hackerone.com/reports/3900615","https://cna.openjsf.org/security-advisories.html","https://github.com/nodejs/undici","https://github.com/nodejs/undici/releases/tag/v6.28.1","https://github.com/nodejs/undici/releases/tag/v7.29.1","https://github.com/nodejs/undici/releases/tag/v8.10.2"],"sourceUrl":"https://github.com/advisories/GHSA-r53p-7pc4-xj5r","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-r53p-7pc4-xj5r","identifiers":["GHSA-r53p-7pc4-xj5r","CVE-2026-18540"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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