{"id":"CVE-2026-1527","published":"2026-03-12T20:17:18Z","modified":"2026-03-13T18:06:03Z","title":"undici is vulnerable to CRLF Injection via upgrade option","vendor":"undici","product":"undici","tier":"tail","description":{"text":"ImpactWhen an application passes user-controlled input to the upgrade option of client.request(), an attacker can inject CRLF sequences (\\r\\n) to:\n\n  *  Inject arbitrary HTTP headers\n  *  Terminate the HTTP request prematurely and smuggle raw data to non-HTTP services (Redis, Memcached, Elasticsearch)\nThe vulnerability exists because undici writes the upgrade value directly to the socket without validating for invalid header characters:\n\n// lib/dispatcher/client-h1.js:1121\nif (upgrade) {\n  header += `connection: upgrade\\r\\nupgrade: ${upgrade}\\r\\n`\n}","provenance":"source","from":"CVE.org"},"cvss":{"score":4.6,"severity":"MEDIUM","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N","provenance":"source","from":"CVE.org CNA"},"epss":{"score":0.00287,"percentile":0.21319,"provenance":"source"},"cwes":[{"id":"CWE-93","name":"Improper Neutralization of CRLF Sequences"}],"references":[{"url":"https://github.com/nodejs/undici/security/advisories/GHSA-4992-7rv2-5pvq","tags":[]},{"url":"https://hackerone.com/reports/3487198","tags":[]},{"url":"https://cna.openjsf.org/security-advisories.html","tags":[]}],"priority":{"score":7.5,"factors":[{"name":"EPSS percentile","points":4.26},{"name":"CVSS severity","points":3.22}]},"vendorSlug":"undici","affectedVersions":[{"vendor":"undici","product":"undici","versions":["< 6.24.0; 7.0.0 < 7.24.0"]}],"affected":[{"ecosystem":"npm","package":"undici","vulnerableRanges":["<6.24.0",">=7.0.0, <7.24.0"],"patched":["6.24.0","7.24.0"],"from":["GHSA-4992-7rv2-5pvq"],"provenance":"source"}],"euvd":{"id":"EUVD-2026-11701","exploited":false,"provenance":"source"},"lineage":{"familyId":"fam-undici-cve-2022-35948","children":[{"from":"CVE-2026-1527","to":"CVE-2026-15157","relation":"incomplete-fix","confidence":"high","kind":"lineage","evidence":[{"kind":"text","provenance":"source","relation":"incomplete-fix","quote":"This is the same defect class as CVE-2022-35948 and CVE-2026-1527, on a header sink that the earlier fixes did not cover.","from":"CVE.org","in":"CVE-2026-15157"}]}]}}