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Vulnerabilities

Vulnerability · CVE-2026-109841

undici is an HTTP client library for Node.js.

Published Oct 15, 2026 · catalog updated Oct 15, 2026 · undici is an HTTP

Check if you run it

No confirmed exploitation is on record for CVE-2026-109841. EPSS is 0.25%. Act only if a listed version of undici is an HTTP is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (undici is an HTTP).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium5.9
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.25%
Remediation
Advisory link
Affected products
Debian:12 node-undici · Debian:13 node-undici · Debian:14 node-undici

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • 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

How to fix CVE-2026-109841

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-109841. EPSS is 0.25%. Act only if a listed version of undici is an HTTP is installed.

Which versions are affected?

Compare what you have installed with 5.15.0+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, 7.15.0+dfsg+~cs3.2.0-1, 7.15.0+dfsg+~cs3.2.0-3, 7.16.0+dfsg+~cs3.2.0-1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-178. EPSS 0.25%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Debian security

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 · OpenSSF OSV / OSV Scanner

    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

Sources

  • CVE.orgVulnerability recordCVE-2026-109841

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-109841

    30-day exploitation probability 0.3%

    first.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
  • OpenSSF OSV / OSV ScannerPackage advisoryDEBIAN-CVE-2026-109841
    osv.dev

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.