{"attribution":"This product uses data from the NVD API but is not endorsed or certified by the NVD.","cve":{"id":"CVE-2026-18540","sourceIdentifier":"ce714d77-add3-4f53-aff5-83d477b104bb","published":"2026-09-04T18:17:50.020","lastModified":"2026-09-16T20:41:17.627","vulnStatus":"Analyzed","cveTags":[],"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."}],"affected":[{"source":"ce714d77-add3-4f53-aff5-83d477b104bb","affectedData":[{"vendor":"undici","product":"undici","defaultStatus":"unaffected","packageURL":"pkg:npm/undici","versions":[{"version":"0","lessThan":"6.28.1","versionType":"semver","status":"affected"},{"version":"6.28.1","versionType":"semver","status":"unaffected"},{"version":"7.0.0","lessThan":"7.29.1","versionType":"semver","status":"affected"},{"version":"7.29.1","versionType":"semver","status":"unaffected"},{"version":"8.0.0","lessThan":"8.10.2","versionType":"semver","status":"affected"},{"version":"8.10.2","versionType":"semver","status":"unaffected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"ce714d77-add3-4f53-aff5-83d477b104bb","type":"Secondary","cvssData":{"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","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"LOW","availabilityImpact":"NONE"},"exploitabilityScore":2.2,"impactScore":1.4}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-09-04T17:50:05.851866Z","id":"CVE-2026-18540","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"ce714d77-add3-4f53-aff5-83d477b104bb","type":"Secondary","description":[{"lang":"en","value":"CWE-444"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*","versionEndExcluding":"6.28.1","matchCriteriaId":"6BF53143-07A7-4006-AC55-66FC8039FF5C"},{"vulnerable":true,"criteria":"cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*","versionStartIncluding":"7.0.0","versionEndExcluding":"7.29.1","matchCriteriaId":"F51DCEB6-C60F-490F-AC91-1C6617CE7716"},{"vulnerable":true,"criteria":"cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*","versionStartIncluding":"8.0.0","versionEndExcluding":"8.10.2","matchCriteriaId":"848B6624-1708-4BF8-B9D7-8F34343D244B"}]}]}],"references":[{"url":"https://cna.openjsf.org/security-advisories.html","source":"ce714d77-add3-4f53-aff5-83d477b104bb","tags":["Vendor Advisory"]},{"url":"https://github.com/nodejs/undici/security/advisories/GHSA-r53p-7pc4-xj5r","source":"ce714d77-add3-4f53-aff5-83d477b104bb","tags":["Mitigation","Vendor Advisory"]}]}}