{"id":"CVE-2026-16728","aliases":["GHSA-8xcm-r25x-g524"],"url":"https://o3.security/vulnerability/CVE-2026-16728","summary":"undici vulnerable to downstream response desynchronization via retry interceptor","details":"undici's retry interceptor can deliver a response whose body length does not match the Content-Length header exposed to the application after a retry or resume of a partial response. In undici before 6.28.0, from 7.0.0 up to before 7.29.0, and from 8.0.0 up to before 8.9.0, a malicious or faulty upstream can return a partial response with a mismatched framing header, close the socket early, and have the retry interceptor assemble a body of a different length while the original Content-Length stays attached. Applications that use the retry interceptor and forward upstream headers and bodies downstream, such as proxies or gateways, may then emit an invalid HTTP response with a stale Content-Length, leading to downstream response desynchronization, connection hangs, or response corruption. Exploitation requires the retry interceptor enabled, an upstream returning a mismatched partial response, and a downstream forwarder that does not remove or recalculate Content-Length. The issue is fixed in undici 6.28.0, 7.29.0, and 8.9.0.","published":"2026-07-29T20:59:02.314Z","modified":"2026-09-10T18:26:51.488396065Z","cvss":{"score":4.8,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N"},"epss":{"score":0.00176,"percentile":0.07407,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"undici","fixedVersion":"6.28.0"},{"ecosystem":"npm","name":"undici","fixedVersion":"7.29.0"},{"ecosystem":"npm","name":"undici","fixedVersion":"8.9.0"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/16xxx/CVE-2026-16728.json"},{"type":"ADVISORY","url":"https://github.com/nodejs/undici/security/advisories/GHSA-8xcm-r25x-g524"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-16728"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-10T18:26:51.488396065Z"}}