CVE-2023-45143 is a low-severity (CVSS 3.9) Information Exposure vulnerability in undici. A fix is available for undici — see the affected versions and patch details below.
Undici's cookie header not cleared on cross-origin redirect in fetch
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 CVE-2023-45143.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
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.
undicinpmDescription
Undici is an HTTP/1.1 client written from scratch for Node.js. Prior to version 5.26.2, Undici already cleared Authorization headers on cross-origin redirects, but did 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 spec, 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 third-party site or a malicious attacker who can control the redirection target (ie. an open redirector) to leak the cookie to the third party site. This was patched in version 5.26.2. There are no known workarounds.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | undici | all versions | 5.26.2npm install undici@5.26.2 |
Affected Products
fedorafedoraprojectundicinodejsDetection & mitigation playbook
Open-source dependencyDetect
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 5.26.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-45143 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.
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.
Since this requires a non-standard configuration, as well as control of the redirection, Red Hat rates this as having a Low impact. Red Hat Developer Hub has included a fix for this.
No current mitigation is available.Source: Red Hat security advisory for CVE-2023-45143 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 8 | nodejs:18-8080020231015215042.63b34585 | RHSA-2023:5869 |
| Red Hat Enterprise Linux 8 | nodejs:20-8090020231019152822.a75119d5 | RHSA-2023:7205 |
| Red Hat Enterprise Linux 9 | nodejs:18-9020020231015221156.rhel9 | RHSA-2023:5849 |
| RHDH-1.1-RHEL-9 | rhdh/rhdh-hub-rhel9:1.1-97 | RHEA-2024:1366 |
Frequently Asked Questions
Is CVE-2023-45143 in your dependencies?
Find it across npm, including transitive dependencies.