GHSA-wqq4-5wpv-mx2g
LOWUndici's cookie header not cleared on cross-origin redirect in fetch
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
undiciReal-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 clears Authorization headers on cross-origin redirects, but does not clear Cookie headers. By design, cookie headers are forbidden request headers, disallowing them to be set in RequestInit.headers in browser environments. Since Undici handles headers more liberally than the specification, there was a disconnect from the assumptions the spec made, and Undici's implementation of fetch.
As such this may lead to accidental leakage of cookie to a 3rd-party site or a malicious attacker who can control the redirection target (ie. an open redirector) to leak the cookie to the 3rd party site.
Patches
This was patched in e041de359221ebeae04c469e8aff4145764e6d76, which is included in version 5.26.2.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | undici | all versions | 5.26.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for undici. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update undici to 5.26.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wqq4-5wpv-mx2g 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.
How O3 protects you
O3 pinpoints whether GHSA-wqq4-5wpv-mx2g is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-wqq4-5wpv-mx2g. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-wqq4-5wpv-mx2g in your dependencies?
O3 detects GHSA-wqq4-5wpv-mx2g across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.