CVE-2026-87866

critical · 9.1

When built with wolfSSL, curl can successfully validate a pinned public key hash against a key the TLS peer does not possess. During the TLS handshake, wolfSSL validates the connection, but curl's subsequent re-parsing of the same certificate - tricked by a manipulated validity length field - extracts and matches a different embedded key, incorrectly authorizing the pinned public key.

9.1

CVSS

0.5%

EPSS (exploit prob.)

43rd

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-295

References

https://curl.se/docs/CVE-2026-87866.html
https://curl.se/docs/CVE-2026-87866.json
https://hackerone.com/reports/3989514
https://hackerone.com/reports/3989514

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2026-87866