{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-18540","assignerOrgId":"ce714d77-add3-4f53-aff5-83d477b104bb","state":"PUBLISHED","assignerShortName":"openjs","dateReserved":"2026-07-31T20:47:28.965Z","datePublished":"2026-09-04T17:15:50.619Z","dateUpdated":"2026-09-04T17:50:13.682Z"},"containers":{"cna":{"providerMetadata":{"orgId":"ce714d77-add3-4f53-aff5-83d477b104bb","shortName":"openjs","dateUpdated":"2026-09-04T17:15:50.619Z"},"descriptions":[{"lang":"en","value":"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.","supportingMedia":[{"type":"text/html","base64":false,"value":"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."}]}],"affected":[{"vendor":"undici","product":"undici","defaultStatus":"unaffected","versions":[{"versionType":"semver","status":"affected","version":"0","lessThan":"6.28.1"},{"versionType":"semver","status":"unaffected","version":"6.28.1"},{"versionType":"semver","status":"affected","version":"7.0.0","lessThan":"7.29.1"},{"versionType":"semver","status":"unaffected","version":"7.29.1"},{"versionType":"semver","status":"affected","version":"8.0.0","lessThan":"8.10.2"},{"versionType":"semver","status":"unaffected","version":"8.10.2"}],"packageURL":"pkg:npm/undici"}],"references":[{"url":"https://github.com/nodejs/undici/security/advisories/GHSA-r53p-7pc4-xj5r"},{"url":"https://cna.openjsf.org/security-advisories.html"}],"credits":[{"lang":"en","type":"reporter","value":"samuel871211"},{"lang":"en","type":"remediation developer","value":"mcollina"},{"lang":"en","type":"remediation reviewer","value":"UlisesGascon"}],"title":"undici vulnerable to downstream response splitting via retry interceptor","metrics":[{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","baseScore":3.7,"baseSeverity":"LOW"},"scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-444","lang":"en","description":"CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')","type":"CWE"}]}],"x_generator":{"engine":"cve-kit 1.0.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-04T17:50:05.851866Z","id":"CVE-2026-18540","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-09-04T17:50:13.682Z"}}]}}