How severe is GHSA-8xcm-r25x-g524?

GHSA-8xcm-r25x-g524 has a CVSS score of 4.8/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-8xcm-r25x-g524?

GHSA-8xcm-r25x-g524 affects the following packages: undici (npm), undici (npm), undici (npm). Ecosystems affected: npm.

How do I fix GHSA-8xcm-r25x-g524?

Update undici to 6.28.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8xcm-r25x-g524 is resolved across your whole dependency graph.

How do I detect GHSA-8xcm-r25x-g524 in my npm dependencies?

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.

How do I mitigate GHSA-8xcm-r25x-g524 if there is no patch (or I can't update yet)?

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.

Is GHSA-8xcm-r25x-g524 actively exploited in the wild?

No public exploit code has been indexed for GHSA-8xcm-r25x-g524 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-8xcm-r25x-g524?

GHSA-8xcm-r25x-g524 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 7th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-8xcm-r25x-g524?

GHSA-8xcm-r25x-g524 is classified as CWE-444 (CWE-444). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-8xcm-r25x-g524 published, and has it been updated?

GHSA-8xcm-r25x-g524 was published on August 3, 2026 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

MEDIUM severity

undici vulnerable to downstream response desynchronization via retry interceptorGHSA-8xcm-r25x-g524

MEDIUMFix: nodejs/undici@1b5a531

GHSA-8xcm-r25x-g524 is a medium-severity (CVSS 4.8) CWE-444 vulnerability in undici. A fix is available for undici — see the affected versions and patch details below.

Also known asCVE-2026-16728

Published

Aug 3, 2026

Updated

Sep 10, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

Exploitation data as of Oct 13, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

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-8xcm-r25x-g524.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs7th percentile — riskier than 7% of all scored CVEsHighest risk

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

How urgent is this, really

GHSA-8xcm-r25x-g524 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 389,824 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

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

9Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream

undicinpm

217.5Mdownloads / week

Description

Impact

Undici's interceptors.retry() can deliver a response whose body length does not match the Content-Length header exposed to the application after a retry or resume of a partial response. Applications that use interceptors.retry() and forward upstream response headers and bodies downstream, for example proxy or gateway applications, may emit an invalid HTTP response with a stale Content-Length header. This can lead to downstream response desynchronization, connection hangs, or response corruption in clients or intermediaries that rely on the forwarded framing metadata.

A malicious or faulty upstream can respond to a range request with a 206 Partial Content response such as:

Content-Range: bytes 0-99/300
Content-Length: 300

and then send only 99 bytes before closing the socket. interceptors.retry() can then retry with Range: bytes=99-99, receive the final byte, and deliver a 100-byte body to the application while the response headers still contain Content-Length: 300 from the first response.

The bug requires interceptors.retry() to be enabled, an upstream that returns a partial response with a mismatched framing header, and a downstream forwarder that does not remove or recalculate Content-Length.

Patches

Patched in undici v6.28.0, v7.29.0, and v8.9.0. Users should upgrade to one of these versions or later.

Workarounds

Disable interceptors.retry() for untrusted upstreams.
Remove or recalculate Content-Length before forwarding a response body assembled or transformed by Undici.

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`undici`	all versions	6.28.0`npm install undici@6.28.0`
📦npm	`undici`	≥ 7.0.0&&< 7.29.0	7.29.0`npm install undici@7.29.0`
📦npm	`undici`	≥ 8.0.0&&< 8.9.0	8.9.0`npm install undici@8.9.0`

Affected Products

1 product · 3 configurations

Application

undicinodejs

≥ 8.0.0 && < 8.9.0

range

Detection & mitigation playbook

Open-source dependency

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.
Fix
Update undici to 6.28.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8xcm-r25x-g524 is resolved across your whole dependency graph.
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 HatModerate

Product	Fixed in	Advisory
Red Hat Hardened Images	`nodejs26-main-11.17.0-1.26.5.1.1.5.hum1`	RHSA-2026:48273
Red Hat Hardened Images	`nodejs24-main-11.16.0-1.24.18.1.0.1.hum1`	RHSA-2026:48537

Frequently Asked Questions

### Impact Undici's `interceptors.retry()` can deliver a response whose body length does not match the `Content-Length` header exposed to the application after a retry or resume of a partial response. Applications that use `interceptors.retry()` and forward upstream response headers and bodies downstream, for example proxy or gateway applications, may emit an invalid HTTP response with a stale `Content-Length` header. This can lead to downstream response desynchronization, connection hangs, or response corruption in clients or intermediaries that rely on the forwarded framing metadata. A mal