---
id: "CVE-2026-94265"
kind: "vulnerability"
aliases: ["CVE-2026-94265"]
title: "curl: HTTP redirect with userinfo leaks Negotiate Kerberos ticket to third parties"
severity: "medium"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["curl", "kerberos", "linux", "negotiate-auth", "runtime", "windows"]
not_affected_if: ["no-kerberos-tickets", "no-negotiate-auth", "no-redirect-following"]
published_at: "2026-10-20T21:17:22+00:00"
first_seen_at: "2026-10-23T21:57:21+00:00"
updated_at: "2026-10-25T05:04:19+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-94265", "first_seen_at": "2026-10-23T21:57:21+00:00"}]
---

# curl: HTTP redirect with userinfo leaks Negotiate Kerberos ticket to third parties

When curl follows an HTTP redirect to a URL containing a username and password, it can keep the original host's HTTP Negotiate authentication state and send it along. A malicious server can use this to make curl send a freshly minted Kerberos ticket, built from the client's ambient identity, to an untrusted third-party host.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `curl --version` and compare against the fixed version in the advisory (unknown in the sources).
- Find scripts or services that call curl with `--negotiate`, `--anyauth` or Kerberos/GSSAPI auth and follow redirects (`-L`).

## Fix

- Upgrade curl to a release that includes the fix (the fixed version is unknown in the sources).
- Until patched, avoid following redirects (`-L`) when using Negotiate auth against untrusted servers.

## Timeline

- 2026-10-23T21:57:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-94265

## From the sources

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 ticket—generated 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`.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_