CVE-2026-87861
cross-origin reuse of a Negotiate connection
CRITICAL
9.1
CVSS Score
Published: October 20, 2026 at 08:09 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
When using ambient user credentials, an HTTP request directed to one origin may be dispatched over a connection previously authenticated via Negotiate for a different origin, leaving the request's intended credentials unused.
Remediation
No guide yetNo remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.
References (3)
Source: cverecord
https://curl.se/docs/CVE-2026-87861.jsonSource: cverecord
https://curl.se/docs/CVE-2026-87861.htmlSource: cverecord
https://hackerone.com/reports/3972094SSVC — 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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