Curl HTTP Redirect Userinfo Leak: Kerberos Ticket Bypass
CVE-2026-94265 Published on October 20, 2026
Authorization: Negotiate sent to foreign origin
When processing an HTTP redirect to a URL containing userinfo (a
`username:password` component), curl might erroneously retain and re-transmit
the original host's HTTP Negotiate authentication state. Consequently, a
malicious server can trigger a redirect containing arbitrary userinfo to force
curl to send a freshly minted Kerberos ticketgenerated using the ambient
identity of the client process to an untrusted third-party host, effectively
bypassing the domain-scoping restrictions normally enforced by the absence of
`--location-trusted`.
Products Associated with CVE-2026-94265
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Affected Versions
curl:- Version 8.22.0, <= 8.22.0 is affected.
- Version 8.21.0, <= 8.21.0 is affected.