CVE-2026-12340
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).
CSIRTS triage
- What
- An out-of-bounds heap read occurs in the computation of the Subject Key Identifier for SM2/SM3 certificates.
- Who is affected
- Deployments using SM2/SM3 certificates.
- Urgency
- Remediation is urgent due to the high severity of the vulnerability, despite no known exploitation.
- Action
- Update the affected libraries handling SM2/SM3 certificates.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.23% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 13% of all EPSS-scored CVEs.
Advisory coverage (2)
External references
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