GHSA-4992-7rv2-5pvq

ghsaUSosv

Undici has CRLF Injection in undici via `upgrade` option

view advisory published 2026-03-13Licence: CC-BY-4.0

### Impact When an application passes user-controlled input to the `upgrade` option of `client.request()`, an attacker can inject CRLF sequences (`\r\n`) to: 1. Inject arbitrary HTTP headers 2. Terminate the HTTP request prematurely and smuggle raw data to non-HTTP services (Redis, Memcached, Elasticsearch) The vulnerability exists because undici writes the `upgrade` value directly to the socket without validating for invalid header characters: ```javascript // lib/dispatcher/client-h1.js:1121 if (upgrade) { header += `connection: upgrade\r\nupgrade: ${upgrade}\r\n` } ``` ### Patches Patched in the undici version v7.24.0 and v6.24.0. Users should upgrade to this version or later. ### Workarounds Sanitize the `upgrade` option string before passing to undici: ```javascript function sanitizeUpgrade(value) { if (/[\r\n]/.test(value)) { throw new Error('Invalid upgrade value') } return value } client.request({ upgrade: sanitizeUpgrade(userInput) }) ```

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describes (1)

Related CVEs.

IDseverity exploitable
CVE-2026-1527US——
ImpactWhen an application passes user-controlled input to the upgrade option of client.request(), an attacker can inject CRLF sequences (\r\n) to: * Inject arbitrary HTTP heade…
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