CVE-2026-87866

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.

EPSS

0.2% chance of exploitation in the next 30 days; higher than 6% of CVEs (scores of 2026-10-25)

Published

2026-10-20

Modified

2026-10-22

Record from

the NVD, synced 2026-10-23

References

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

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