CVE-2026-94265

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HTTP Redirect Negotiate Authentication State Exposure in cURL

Publication date: 2026-10-20

Last updated on: 2026-10-30

Assigner: curl

Description

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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Meta Information

Published

2026-10-20

Last Modified

2026-10-30

Generated

2026-11-10

AI Q&A

2026-10-21

EPSS Evaluated

2026-11-08

NVD

CVE-2026-94265

Affected Vendors & Products

Vendor	Product	Version / Range
curl	curl	8.22.0
curl	curl	8.21.0

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-200	The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.

Attack-Flow Graph

Executive Summary

This vulnerability involves curl incorrectly handling HTTP redirects with userinfo (username:password) in the URL. When curl follows such a redirect, it may reuse authentication credentials from the original host, sending them to an untrusted third-party server. This bypasses domain restrictions meant to prevent unauthorized access.

Detection Guidance

To detect this vulnerability, monitor network traffic for HTTP redirects containing userinfo (username:password) components. Check if curl sends Kerberos tickets to untrusted hosts after such redirects. Use packet capture tools like tcpdump or Wireshark to inspect HTTP headers and authentication headers.

Impact Analysis

If exploited, this flaw could allow an attacker to capture your authentication credentials or Kerberos tickets when curl follows a malicious redirect. This may lead to unauthorized access to sensitive data or systems, depending on the permissions of the stolen credentials.

Compliance Impact

This vulnerability could potentially violate compliance with GDPR and HIPAA by enabling unauthorized transmission of authentication credentials (Kerberos tickets) to untrusted third-party hosts. This may result in unauthorized data access or exposure, compromising data protection requirements under these regulations.

Mitigation Strategies

Avoid using curl with HTTP redirects or upgrade to a patched version if available. Disable automatic re-authentication in curl configurations and monitor network traffic for suspicious Kerberos ticket transmissions.

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