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CVE-2023-45143 Low

Undici's cookie header not cleared on cross-origin redirect in fetch

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.

Exploit probability 1.2%
Published October 12, 2023
Required by Not available
Last source change August 12, 2026

02 / AFFECTED SOFTWARE

Affected packages

Unknown Unknown

129 explicit affected versions

npm undici

03 / CONNECTIONS

Connected vulnerabilities

04 / EVIDENCE

Source records

Open Source Vulnerabilities GHSA-wqq4-5wpv-mx2g

### Impact Undici clears Authorization headers on cross-origin redirects, but does not clear `Cookie` headers. By design, `cookie` headers are [forbidden request headers](https://fetch.spec.whatwg.org/#forbidden-request-header), 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](https://github.com/nodejs/undici/commit/e041de359221ebeae04c469e8aff4145764e6d76), which is included in version 5.26.2.

View original source
Open Source Vulnerabilities CVE-2023-45143

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.

View original source

05 / REFERENCES

Further evidence