What’s Vulnerable › Vulnerabilities

CVE-2026-40253: openCryptoki: Memory safety vulnerabilities in BER/DER decoders in asn1.c

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-04-16 · updated 2026-06-17
• Weakness: CWE-125

Description

openCryptoki is a PKCS#11 library and provides tooling for Linux and AIX. In versions 3.26.0 and below, the BER/DER decoding functions in the shared common library (asn1.c) accept a raw pointer but no buffer length parameter, and trust attacker-controlled BER length fields without validating them against actual buffer boundaries. All primitive decoders are affected: ber_decode_INTEGER, ber_decode_SEQUENCE, ber_decode_OCTET_STRING, ber_decode_BIT_STRING, and ber_decode_CHOICE. Additionally, ber_decode_INTEGER can produce integer underflows when the encoded length is zero. An attacker supplying a malformed BER-encoded cryptographic object through PKCS#11 operations such as C_CreateObject or C_UnwrapKey, token loading from disk, or remote backend communication can trigger out-of-bounds reads. This affects all token backends (Soft, ICA, CCA, TPM, EP11, ICSF) since the vulnerable code is in the shared common library. A patch is available thorugh commit ed378f463ef73364c89feb0fc923f4dc867332a3.

Affected products

• opencryptoki: through 3.26.0

References

• https://github.com/opencryptoki/opencryptoki/commit/ed378f463ef73364c89feb0fc923f4dc867332a3
• https://github.com/opencryptoki/opencryptoki/security/advisories/GHSA-c9cf-6vr4-wfxm
• https://github.com/opencryptoki/opencryptoki/security/advisories/GHSA-c9cf-6vr4-wfxm

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