CVE-2026-86414

critical · 9.1

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:`.

9.1

CVSS

0.3%

EPSS (exploit prob.)

19th

EPSS percentile

2026-10-20

Published

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Weaknesses

CWE-201

References

https://curl.se/docs/CVE-2026-86414.html
https://curl.se/docs/CVE-2026-86414.json
https://hackerone.com/reports/3993566
https://hackerone.com/reports/3993566

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2026-86414