openCryptoki implements PKCS#11 functionality with a shared library that decodes BER/DER data. The decoder functions take a raw pointer but do not accept a buffer length and blindly trust attacker-controlled BER length fields, permitting out-of-bounds reads and integer underflows when the encoded length is zero. This flaw is a classic heap memory safety weakness (CWE‑125) that can be leveraged by an adversary to read arbitrary memory of the process. The impact is a leakage of data and possible compromise of integrity of cryptographic objects.

The vulnerability is present in openCryptoki version 3.26.0 and earlier, affecting all token backends—Soft, ICA, CCA, TPM, EP11, and ICFS—because the flawed code resides in the shared common library. Any installation of the openCryptoki library older than 3.26.0 that performs PKCS#11 operations such as object creation or key unwrapping is susceptible.

The CVSS score of 6.8 indicates a medium severity flaw. An explicit EPSS score is not available, and the vulnerability is not listed in KEV. An attacker who can supply a crafted BER-encoded cryptographic object to the PKCS#11 interface—via calls such as C_CreateObject or C_UnwrapKey, during token loading from disk, or through remote backend communication—can exploit the decoder to expose or corrupt memory. The attack path requires the attacker to influence input to the library, and the exploit can be triggered over a local or networked PKCS#11 client.