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CVE-2026-109841

undici is an HTTP client library for Node.js.

Published Oct 15, 2026 · updated Oct 15, 2026

undici is an HTTP client library for Node.js. In versions 7.15.0 through 7.30.0 and 8.0.0 through 8.12.1, its fetch() implementation verifies Subresource Integrity metadata by matching the algorithm token against a lowercase-only set, even though the SRI specification defines the token by its ASCII-lowercase form, so a valid but non-lowercase token such as an uppercase or mixed-case SHA256 is treated as unknown and skipped. When no recognized algorithm remains, undici treats the integrity list as empty and accepts the response, so a server returning a body that does not match the pinned digest passes the check. An attacker who controls only the response body can therefore deliver attacker-controlled bytes to an application that pinned a valid uppercase or mixed-case SRI token, with no integrity error, affecting response integrity only. The issue is fixed in undici 7.30.1 and 8.12.2, which normalize the algorithm token to ASCII lowercase before validation, and users should upgrade to one of those versions or later. As a workaround, use lowercase algorithm tokens such as sha256, sha384, or sha512 in integrity metadata.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 15, 2026 · NIST NVD

    Detected

    undici is an HTTP client library for Node.js. In versions 7.15.0 through 7.30.0 and 8.0.0 through 8.12.1, its fetch() implementation verifies Subresource Integrity metadata by matching the algorithm token against a lowercase-only set, even though the SRI specification defines the token by its ASCII-lowercase form, so a valid but non-lowercase token such as an uppercase or mixed-case SHA256 is trea

  2. Oct 15, 2026 · OSV.dev

    Updated

    undici is an HTTP client library for Node.js. In versions 7.15.0 through 7.30.0 and 8.0.0 through 8.12.1, its fetch() implementation verifies Subresource Integrity metadata by matching the algorithm token against a lowercase-only set, even though the SRI specification defines the token by its ASCII-lowercase form, so a valid but non-lowercase token such as an uppercase or mixed-case SHA256 is trea

Affected

  • Debian:12 node-undici5.15.0+dfsg1+~cs20.10.9.3-1, 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u1, 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u2
  • Debian:13 node-undici7.15.0+dfsg+~cs3.2.0-1, 7.15.0+dfsg+~cs3.2.0-3, 7.16.0+dfsg+~cs3.2.0-1
  • Debian:14 node-undici7.15.0+dfsg+~cs3.2.0-1, 7.15.0+dfsg+~cs3.2.0-3, 7.16.0+dfsg+~cs3.2.0-1

Sources

  • CVE.orgVulnerability recordCVE-2026-109841

    Official CVE identifier

    cve.org
  • NIST NVDVulnerability recordCVE-2026-109841

    undici is an HTTP client library for Node.js. In versions 7.15.0 through 7.30.0 and 8.0.0 through 8.12.1, its fetch() implementation verifies Subresource Integrity metadata by matching the algorithm token against a lowercase-only set, even though the SRI specification defines the

    nvd.nist.gov
  • OSV.devPackage advisoryDEBIAN-CVE-2026-109841
    osv.dev

References