Out-of-bounds Read in Wolfssl
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).
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.003 (20.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 20th percentile — 20.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Wolfssl — versions 5.6.4
Weakness classification (CWE)
References
- github.com/wolfSSL/wolfssl/pull/10641 (Patch, patch, Issue Tracking)
- www.wolfssl.com/docs/security-vulnerabilities/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-12340?
- CVE-2026-12340 is a high-severity vulnerability in Wolfssl, classified under Out-of-bounds Read. CVSS score: 7.5/10. Published 2026-06-25.
- How severe is CVE-2026-12340?
- High severity. CVSS v3 base score is 7.5 out of 10.