Vulnerability in Undici

CVE-2026-120423

undici is an HTTP client for Node.js. In versions 7.15.0 through 7.30.1 and 8.0.0 through 8.12.3, fetch verifies Subresource Integrity metadata by splitting the integrity string on a single space, but the SRI grammar separates metadata by ASCII whitespace, which also includes the horizontal tab. An integrity value whose digest is preceded by a tab or other ASCII whitespace is parsed as a single unrecognized token and skipped, and when no recognized algorithm remains undici treats the integrity list as empty and accepts the response, so a server returning a body different from the pinned digest passes the check. An application that pins a response with a valid but whitespace-surrounded SRI value receives attacker-controlled bytes with no integrity error, and the attacker needs only to control the response body, not the integrity metadata. The issue is fixed in undici 7.30.2 and 8.12.4, and users should upgrade to one of those versions or later. As a workaround, supply SRI integrity metadata without surrounding whitespace, using a single space to separate multiple digests.

Published 2026-11-06 · last modified 2026-11-06.