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Not in CISA KEV
HIGH severity

undici vulnerable to Denial of Service via unhandled error on excessive content-encodingsGHSA-xjj6-f33q-929c

HIGHFix: nodejs/undici@07ded49

GHSA-xjj6-f33q-929c is a high-severity (CVSS 7.5) CWE-248 vulnerability in undici. A fix is available for undici — see the affected versions and patch details below.

Also known asCVE-2026-109869
Published
Updated
Affected
3 pkgs
Patched
3 / 3
Exploits
None indexed
Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-xjj6-f33q-929c.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs27th percentile — riskier than 27% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

GHSA-xjj6-f33q-929c by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

3 pkgs affected
📦undici📦undici📦undici

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

Impact

undici's fetch() crashes the Node.js process when a malicious server returns a response with more than five content codings and closes the connection before sending the body. undici rejects such responses (a content-encoding limit), but it created the internal response stream before that check and returned without attaching an error listener or aborting the request. The early close then surfaces a content-length mismatch on that orphaned internal stream, which Node.js treats as an unhandled error and terminates the process. A remote, unauthenticated server can trigger this with a single response, even when the application correctly catches the fetch() rejection. undici 6.x, 7.x, and 8.x are affected.

Patches

Upgrade to 6.29.1, 7.30.1, or 8.12.2. undici now validates the content-encoding chain before creating the internal body stream and aborts the response when the limit is exceeded, so no error can surface on an orphaned stream.

Workarounds

None.

Affected Packages

3 total 3 fixed
EcosystemPackageVulnerable rangeFix
📦npmundici≥ 6.23.0&&< 6.29.16.29.1npm install undici@6.29.1
📦npmundici≥ 7.18.0&&< 7.30.17.30.1npm install undici@7.30.1
📦npmundici≥ 8.0.0&&< 8.12.28.12.2npm install undici@8.12.2

Affected Products

1 product · 3 configurations
Application
undicinodejs
≥ 8.0.0 && < 8.12.2
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for undici, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update undici to 6.29.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xjj6-f33q-929c is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant
ProductFixed inAdvisory
Red Hat Hardened Imagesnodejs26-main-11.20.0-1.26.11.1.0.4.hum1RHSA-2026:84657
Red Hat Hardened Imagesnodejs24-main-11.19.0-1.24.21.0.1.5.hum1RHSA-2026:84706
Red Hat Hardened Imagesnodejs26-main-11.20.0-1.26.12.1.0.1.hum1RHSA-2026:87703

Frequently Asked Questions

### Impact undici's `fetch()` crashes the Node.js process when a malicious server returns a response with more than five content codings and closes the connection before sending the body. undici rejects such responses (a content-encoding limit), but it created the internal response stream before that check and returned without attaching an error listener or aborting the request. The early close then surfaces a content-length mismatch on that orphaned internal stream, which Node.js treats as an unhandled `error` and terminates the process. A remote, unauthenticated server can trigger this with
O3 Security · Impact-Aware SCA

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undici vulnerable to Denial of Service via unhandled error…