What’s Vulnerable › Vulnerabilities

CVE-2026-86413: Negotiate credentials sent to redirected origin

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-20 · updated 2026-10-30
• Weakness: CWE-201

Description

When using an *ambient user* in a first transfer doing Negotiate authentication and asked to follow redirects, curl could pass on its credential details to an unrelated second origin when asked to redirect there.

Affected products

• curl: from 8.22.0 through 8.22.0; from 8.21.0 through 8.21.0

References

• https://curl.se/docs/CVE-2026-86413.html
• https://curl.se/docs/CVE-2026-86413.json
• https://hackerone.com/reports/3993549
• https://hackerone.com/reports/3993549

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