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CVE-2026-109841

7.5, high

undici is an HTTP client library for Node.js

NVD (opens in a new tab) CVE.org (opens in a new tab)
CVSS
7.5, high high CVSS v3.1
EPSS, next 30 days
0.3% higher than 15.2% of scored CVEs
Exploitation
No public evidence
Published
15 Oct 20265 days ago

Description

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.

Details

Vendor
Undici
Product
undici
Weakness
CWE-178 (opens in a new tab)
Status
Analyzed
Updated
19 Oct 2026
Assigner
ce714d77-add3-4f53-aff5-83d477b104bb

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References 2

Advisories 2

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Undici CVEs

Every Undici CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-109383 undici is an HTTP client library for Node.js EPSS 0.2% 9.1, critical
  • CVE-2026-109829 undici is an HTTP client library for Node.js EPSS 0.1% 9.1, critical
  • CVE-2026-109924 undici Allocation of Resources Without Limits or Throttling Vulnerability EPSS 0.3% 7.5, high
  • CVE-2026-109932 undici Uncontrolled Resource Consumption Vulnerability EPSS 0.3% 7.5, high
  • CVE-2026-87029 undici is an HTTP client library for Node.js EPSS 0.3% 7.5, high
  • CVE-2026-84961 undici's BalancedPool constructor passes its entire options object through an internal deep-clone that serializes and reparses the value… EPSS 0.1% 9.1, critical
  • CVE-2026-84933 undici Exposure of Sensitive Information Vulnerability EPSS 0.3% 8.2, high
  • CVE-2026-85014 undici's experimental WebSocketStream client crashes the whole Node.js process when a remote peer closes the TCP connection without a… EPSS 0.4% 7.5, high

Beyond this page

Is CVE-2026-109841 in your network?

This page tells you how dangerous CVE-2026-109841 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

  • EXYS7600 OCELOT

    Find it before attackers do

    Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2026-109841 comes with the devices to patch.

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  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

    Learn more about EXYS7950 KONDRA
Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 20 Oct 2026, not the live upstream state.