🔐 CVE Alert

CVE-2026-87866

UNKNOWN 0.0

wolfSSL public-key pinning bypass

CVSS Score
0.0
EPSS Score
0.0%
EPSS Percentile
0th

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.

Vendor curl
Product curl
Published Oct 20, 2026
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Affected Versions

curl / curl
8.22.0 ≤ 8.22.0 8.21.0 ≤ 8.21.0 8.20.0 ≤ 8.20.0 8.19.0 ≤ 8.19.0 8.18.0 ≤ 8.18.0 8.17.0 ≤ 8.17.0 8.16.0 ≤ 8.16.0 8.15.0 ≤ 8.15.0 8.14.1 ≤ 8.14.1 8.14.0 ≤ 8.14.0 8.13.0 ≤ 8.13.0 8.12.1 ≤ 8.12.1 8.12.0 ≤ 8.12.0 8.11.1 ≤ 8.11.1 8.11.0 ≤ 8.11.0 8.10.1 ≤ 8.10.1 8.10.0 ≤ 8.10.0 8.9.1 ≤ 8.9.1 8.9.0 ≤ 8.9.0 8.8.0 ≤ 8.8.0 8.7.1 ≤ 8.7.1 8.7.0 ≤ 8.7.0 8.6.0 ≤ 8.6.0 8.5.0 ≤ 8.5.0 8.4.0 ≤ 8.4.0 8.3.0 ≤ 8.3.0 8.2.1 ≤ 8.2.1 8.2.0 ≤ 8.2.0 8.1.2 ≤ 8.1.2 8.1.1 ≤ 8.1.1 8.1.0 ≤ 8.1.0 8.0.1 ≤ 8.0.1 8.0.0 ≤ 8.0.0 7.88.1 ≤ 7.88.1 7.88.0 ≤ 7.88.0 7.87.0 ≤ 7.87.0 7.86.0 ≤ 7.86.0 7.85.0 ≤ 7.85.0 7.84.0 ≤ 7.84.0 7.83.1 ≤ 7.83.1 7.83.0 ≤ 7.83.0 7.82.0 ≤ 7.82.0 7.81.0 ≤ 7.81.0 7.80.0 ≤ 7.80.0 7.79.1 ≤ 7.79.1 7.79.0 ≤ 7.79.0 7.78.0 ≤ 7.78.0 7.77.0 ≤ 7.77.0 7.76.1 ≤ 7.76.1 7.76.0 ≤ 7.76.0 7.75.0 ≤ 7.75.0 7.74.0 ≤ 7.74.0 7.73.0 ≤ 7.73.0 7.72.0 ≤ 7.72.0 7.71.1 ≤ 7.71.1 7.71.0 ≤ 7.71.0 7.70.0 ≤ 7.70.0 7.69.1 ≤ 7.69.1 7.69.0 ≤ 7.69.0 7.68.0 ≤ 7.68.0 7.67.0 ≤ 7.67.0 7.66.0 ≤ 7.66.0 7.65.3 ≤ 7.65.3 7.65.2 ≤ 7.65.2 7.65.1 ≤ 7.65.1 7.65.0 ≤ 7.65.0 7.64.1 ≤ 7.64.1 7.64.0 ≤ 7.64.0 7.63.0 ≤ 7.63.0 7.62.0 ≤ 7.62.0 7.61.1 ≤ 7.61.1 7.61.0 ≤ 7.61.0 7.60.0 ≤ 7.60.0 7.59.0 ≤ 7.59.0 7.58.0 ≤ 7.58.0 7.57.0 ≤ 7.57.0 7.56.1 ≤ 7.56.1 7.56.0 ≤ 7.56.0 7.55.1 ≤ 7.55.1 7.55.0 ≤ 7.55.0 7.54.1 ≤ 7.54.1 7.54.0 ≤ 7.54.0 7.53.1 ≤ 7.53.1 7.53.0 ≤ 7.53.0 7.52.1 ≤ 7.52.1 7.52.0 ≤ 7.52.0 7.51.0 ≤ 7.51.0 7.50.3 ≤ 7.50.3 7.50.2 ≤ 7.50.2 7.50.1 ≤ 7.50.1 7.50.0 ≤ 7.50.0 7.49.1 ≤ 7.49.1 7.49.0 ≤ 7.49.0 7.48.0 ≤ 7.48.0 7.47.1 ≤ 7.47.1 7.47.0 ≤ 7.47.0 7.46.0 ≤ 7.46.0 7.45.0 ≤ 7.45.0 7.44.0 ≤ 7.44.0 7.43.0 ≤ 7.43.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗
curl.se: https://curl.se/docs/CVE-2026-87866.json curl.se: https://curl.se/docs/CVE-2026-87866.html hackerone.com: https://hackerone.com/reports/3989514

Credits

Muhamad Arga Reksapati Stefan Eissing