CVE-2026-12340: wolfSSL

High severity, CVSS 7.5. EPSS: 0.3% chance of exploitation in the next 30 days.

Out-of-bounds heap read during SM2/SM3 certificate signature verification. When parsing a certificate with an SM3wSM2 signature, the Subject Key Identifier computation reads the trailing 65 bytes of the public key without checking that the key is at least that long. A public key shorter than 65 bytes results in an out-of-bounds heap read, leading to a potential crash (denial of service); there is no out-of-bounds write. Note this only affects builds with SM2 support (--enable-sm2 or --enable-all).

Affected products

• wolfSSL wolfSSL: from 5.6.4, before 5.9.2 (fixed in 5.9.2)

Published 2026-06-25. Last modified 2026-06-26.