CVE-2026-87866 is a vulnerability in Haxx Curl
Published on October 20, 2026
wolfSSL public-key pinning bypass
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.
Products Associated with CVE-2026-87866
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Affected Versions
curl:- Version 8.22.0, <= 8.22.0 is affected.
- Version 8.21.0, <= 8.21.0 is affected.
- Version 8.20.0, <= 8.20.0 is affected.
- Version 8.19.0, <= 8.19.0 is affected.
- Version 8.18.0, <= 8.18.0 is affected.
- Version 8.17.0, <= 8.17.0 is affected.
- Version 8.16.0, <= 8.16.0 is affected.
- Version 8.15.0, <= 8.15.0 is affected.
- Version 8.14.1, <= 8.14.1 is affected.
- Version 8.14.0, <= 8.14.0 is affected.
- Version 8.13.0, <= 8.13.0 is affected.
- Version 8.12.1, <= 8.12.1 is affected.
- Version 8.12.0, <= 8.12.0 is affected.
- Version 8.11.1, <= 8.11.1 is affected.
- Version 8.11.0, <= 8.11.0 is affected.
- Version 8.10.1, <= 8.10.1 is affected.
- Version 8.10.0, <= 8.10.0 is affected.
- Version 8.9.1, <= 8.9.1 is affected.
- Version 8.9.0, <= 8.9.0 is affected.
- Version 8.8.0, <= 8.8.0 is affected.
- Version 8.7.1, <= 8.7.1 is affected.
- Version 8.7.0, <= 8.7.0 is affected.
- Version 8.6.0, <= 8.6.0 is affected.
- Version 8.5.0, <= 8.5.0 is affected.
- Version 8.4.0, <= 8.4.0 is affected.
- Version 8.3.0, <= 8.3.0 is affected.
- Version 8.2.1, <= 8.2.1 is affected.
- Version 8.2.0, <= 8.2.0 is affected.
- Version 8.1.2, <= 8.1.2 is affected.
- Version 8.1.1, <= 8.1.1 is affected.
- Version 8.1.0, <= 8.1.0 is affected.
- Version 8.0.1, <= 8.0.1 is affected.
- Version 8.0.0, <= 8.0.0 is affected.
- Version 7.88.1, <= 7.88.1 is affected.
- Version 7.88.0, <= 7.88.0 is affected.
- Version 7.87.0, <= 7.87.0 is affected.
- Version 7.86.0, <= 7.86.0 is affected.
- Version 7.85.0, <= 7.85.0 is affected.
- Version 7.84.0, <= 7.84.0 is affected.
- Version 7.83.1, <= 7.83.1 is affected.
- Version 7.83.0, <= 7.83.0 is affected.
- Version 7.82.0, <= 7.82.0 is affected.
- Version 7.81.0, <= 7.81.0 is affected.
- Version 7.80.0, <= 7.80.0 is affected.
- Version 7.79.1, <= 7.79.1 is affected.
- Version 7.79.0, <= 7.79.0 is affected.
- Version 7.78.0, <= 7.78.0 is affected.
- Version 7.77.0, <= 7.77.0 is affected.
- Version 7.76.1, <= 7.76.1 is affected.
- Version 7.76.0, <= 7.76.0 is affected.
- Version 7.75.0, <= 7.75.0 is affected.
- Version 7.74.0, <= 7.74.0 is affected.
- Version 7.73.0, <= 7.73.0 is affected.
- Version 7.72.0, <= 7.72.0 is affected.
- Version 7.71.1, <= 7.71.1 is affected.
- Version 7.71.0, <= 7.71.0 is affected.
- Version 7.70.0, <= 7.70.0 is affected.
- Version 7.69.1, <= 7.69.1 is affected.
- Version 7.69.0, <= 7.69.0 is affected.
- Version 7.68.0, <= 7.68.0 is affected.
- Version 7.67.0, <= 7.67.0 is affected.
- Version 7.66.0, <= 7.66.0 is affected.
- Version 7.65.3, <= 7.65.3 is affected.
- Version 7.65.2, <= 7.65.2 is affected.
- Version 7.65.1, <= 7.65.1 is affected.
- Version 7.65.0, <= 7.65.0 is affected.
- Version 7.64.1, <= 7.64.1 is affected.
- Version 7.64.0, <= 7.64.0 is affected.
- Version 7.63.0, <= 7.63.0 is affected.
- Version 7.62.0, <= 7.62.0 is affected.
- Version 7.61.1, <= 7.61.1 is affected.
- Version 7.61.0, <= 7.61.0 is affected.
- Version 7.60.0, <= 7.60.0 is affected.
- Version 7.59.0, <= 7.59.0 is affected.
- Version 7.58.0, <= 7.58.0 is affected.
- Version 7.57.0, <= 7.57.0 is affected.
- Version 7.56.1, <= 7.56.1 is affected.
- Version 7.56.0, <= 7.56.0 is affected.
- Version 7.55.1, <= 7.55.1 is affected.
- Version 7.55.0, <= 7.55.0 is affected.
- Version 7.54.1, <= 7.54.1 is affected.
- Version 7.54.0, <= 7.54.0 is affected.
- Version 7.53.1, <= 7.53.1 is affected.
- Version 7.53.0, <= 7.53.0 is affected.
- Version 7.52.1, <= 7.52.1 is affected.
- Version 7.52.0, <= 7.52.0 is affected.
- Version 7.51.0, <= 7.51.0 is affected.
- Version 7.50.3, <= 7.50.3 is affected.
- Version 7.50.2, <= 7.50.2 is affected.
- Version 7.50.1, <= 7.50.1 is affected.
- Version 7.50.0, <= 7.50.0 is affected.
- Version 7.49.1, <= 7.49.1 is affected.
- Version 7.49.0, <= 7.49.0 is affected.
- Version 7.48.0, <= 7.48.0 is affected.
- Version 7.47.1, <= 7.47.1 is affected.
- Version 7.47.0, <= 7.47.0 is affected.
- Version 7.46.0, <= 7.46.0 is affected.
- Version 7.45.0, <= 7.45.0 is affected.
- Version 7.44.0, <= 7.44.0 is affected.
- Version 7.43.0, <= 7.43.0 is affected.