CVE-2026-109841: undici is an HTTP client library for Node.js

Q: How do I fix CVE-2026-109841?

undici: upgrade to 7.30.1, 8.12.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-109841 being exploited?

CVE-2026-109841 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-109841 affect?

CVE-2026-109841 affects undici. Severity is medium (CVSS 5.9). 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

Q: How urgent is CVE-2026-109841?

Priority 30/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 5.9REMOTEUPGRADE

CVE-2026-109841 is a medium-severity flaw (CVSS 5.9) affecting undici. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 alg

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 84%)
CISA exploited list	No
Weakness	CWE-178
Published	2026-10-15
Last modified	2026-10-19

Publisher (CNA): openjs · Vendor: nodejs

Last updated 2026-10-19 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-10-15 19:17 UTCPublished CVE record published
2026-10-19 20:45 UTCUpdated Record last modified

nodejs undici UPGRADE

Affected: >= 7.15.0 and < 7.30.1 · >= 8.0.0 and < 8.12.2

Fixed in: 7.30.1, 8.12.2

Safe to downgrade to: a release before 7.15.0

1. Check installed version

npm ls undici

2. UPGRADE to 7.30.1

npm install undici@">=7.30.1"

3. If no update is available yet, DOWNGRADE to a release before 7.15.0

npm view undici versions npm install undici@"<7.15.0"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-109841?

undici: upgrade to 7.30.1, 8.12.2. Exact commands for each OS are on this page.

Is CVE-2026-109841 being exploited?

CVE-2026-109841 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-109841 affect?

CVE-2026-109841 affects undici. Severity is medium (CVSS 5.9). 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

How urgent is CVE-2026-109841?

Priority 30/100. Remotely exploitable, no login, no user action

Software pages

Node.js vulnerabilities

Related CVEs

CVE-2026-109855 HIGH 7.5 UPGRADE undici is an HTTP client library for Node.js
CVE-2026-109383 HIGH 7.4 UPGRADE undici is an HTTP client library for Node.js
CVE-2026-109829 HIGH 7.4 UPGRADE undici is an HTTP client library for Node.js
CVE-2026-109869 HIGH 7.5 UPGRADE undici is an HTTP client library for Node.js
CVE-2026-109924 MEDIUM 5.9 UPGRADE undici is an HTTP client library for Node.js

References

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