CVE-2026-40253

A flaw was found in openCryptoki, a PKCS#11 (Cryptographic Token Interface Standard) library. The BER/DER (Basic Encoding Rules/Distinguished Encoding Rules) decoding functions in the shared common library do not properly validate attacker-controlled length fields against actual buffer boundaries. This allows an attacker to supply a malformed BER-encoded cryptographic object, potentially through PKCS#11 operations, token loading, or remote backend communication. This can lead to out-of-bounds reads and integer underflows, resulting in information disclosure and a denial of service.

A moderate severity input validation flaw affects openCryptoki, the PKCS#11 (Cryptographic Token Interface Standard) implementation shipped in Red Hat Enterprise Linux. The BER/DER decoding functions in openCryptoki's shared common library (asn1.c) accept a raw pointer without a buffer length parameter and trust attacker-controlled BER length fields without validating them against the actual buffer boundaries. An attacker who can supply a malformed BER-encoded cryptographic object, for example through PKCS#11 operations such as C_CreateObject or C_UnwrapKey, through loading of a crafted token object from disk, or via remote backend communication, can trigger out-of-bounds reads and integer underflows, resulting in information disclosure and denial of service. Because the vulnerable code resides in the shared common library, all token backends (Soft, ICA, CCA, TPM, EP11, ICSF) are affected. The flaw is rated Moderate severity (CVSS 3.1 score 6.8, AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H), matching the upstream and CVEORG assessments; the NVD score (6.1) differs only marginally and does not change the severity classification. The openCryptoki package in Red Hat Enterprise Linux 6, 7, 8, 9, and 10 is affected: fixes are being pursued for maintained update streams, while the fix is deferred for several older update streams, where the residual risk remains the out-of-bounds read leading to information disclosure and denial of service. The related packages libica, openssl-ibmca, and openssl-ibmpkcs11, and Fedora's opencryptoki package, are not affected because the vulnerable code is not present.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.