by Kastro
Paper/Archive/CVE-2026-87861

CVE-2026-87861

curl curl — cross-origin reuse of a Negotiate connection

EPSS 0.3%public exploitCVSS 9.1
critical.is priorityof 100
41
CVSS 9.1 (ADP)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 18.6.186 × 203.7Exploit: SSVC poc+1010.0SSVC exploitation: poc+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
curl8.22.0 – 8.22.0–CNA
curl8.21.0 – 8.21.0–CNA

Scores by source

CISA ADP9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CISA ADPSSVCExploitation: poc · Automatable: yes · Technical impact: total

References

refcurl.se/docs/CVE-2026-87861.jsonrefcurl.se/docs/CVE-2026-87861.htmlexploithackerone.com/reports/3972094