CVE-2026-86414

leaking host credentials to HTTP proxy

CRITICAL
9.1
CVSS Score
Published: October 20, 2026 at 08:07 PM UTC
Updated: October 30, 2026 at 12:16 PM UTC
1 product affected across 1 vendorCurl

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Severity
CRITICAL9.1
Exploit prediction
EPSS 0.7%
SSVC
PoC

Description

An HTTP proxy can trick libcurl into sending the origin's credentials (Basic password, or a Negotiate/Kerberos ticket) to the proxy itself, by answering the `CONNECT` tunnel request with 401 `WWW-Authenticate:` instead of the expected 407 `Proxy-Authenticate:`.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCPoCAutomatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

9.1CRITICALCISA-ADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-201

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