CVE-2026-12340 json
Out-of-bounds heap read in SM2/SM3 certificate Subject Key Identifier computation
published 2026-06-25 4 mo ago modified 2026-07-25 3 mo ago also EUVD-2026-39547 , GHSA-q349-x427-xg3w , JLSEC-2026-700
- cvss
- 7.5
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 22%
- public exploits
- 0
- none known
Summary
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).
Patch / fix
- julia wolfSSL_jll 5.9.2+0
- wolfssl wolfssl 5.9.2
- wolfssl Alpine 3.24 5.9.2-r0
alpine advisories ALPINE-CVE-2026-12340
Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0
- github.com/wolfSSL/wolfssl#10641 pull request
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 4 mo ago
Exploit prediction
0.30% chance of exploitation in the next 30 days, higher than 22% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 6.3 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N |
| CNA | 4.0 | 6.3 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
| NVD | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| OSV | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| julia | wolfSSL_jll | >=5.7.2+0, <5.9.2+0 |
5.9.2+0 |
Affected products
- wolfSSL wolfSSL
Classification
- Weakness
-
- CWE-125 Out-of-bounds Read
References
-
github.com
/wolfSSL/wolfssl/pull/10641
patch, issue-tracking, web
-
wolfssl.com
/docs/security-vulnerabilities/
vendor-advisory, web
-
github.com
/advisories/GHSA-q349-x427-xg3w
web
-
nvd.nist.gov
/vuln/detail/CVE-2026-12340
web
-
wolfssl.com
/docs/security-vulnerabilities
web
Sources
- CVE List CVE-2026-12340
- NVD CVE-2026-12340
- OSV JLSEC-2026-700
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