Issue summary: An invalid or NULL pointer dereference can happen in an application processing a malformed PKCS#12 file. Impact summary: An application processing a malformed PKCS#12 file can be caused to dereference an invalid or NULL pointer on memory read, resulting in a Denial of Service. A type confusion vulnerability exists in PKCS#12 parsing code where an ASN1_TYPE union member is accessed without first validating the type, causing an invalid pointer read. The location is constrained to a 1-byte address space, meaning any attempted pointer manipulation can only target addresses between 0x00 and 0xFF. This range corresponds to the zero page, which is unmapped on most modern operating systems and will reliably result in a crash, leading only to a Denial of Service. Exploiting this issue also requires a user or application to process a maliciously crafted PKCS#12 file. It is uncommon to accept untrusted PKCS#12 files in applications as they are usually used to store private keys which are trusted by definition. For these reasons, the issue was assessed as Low severity. The FIPS modules in 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the PKCS12 implementation is outside the OpenSSL FIPS module boundary. OpenSSL 3.6, 3.5, 3.4, 3.3, 3.0 and 1.1.1 are vulnerable to this issue. OpenSSL 1.0.2 is not affected by this issue.
https://openssl-library.org/news/secadv/20260127.txt
https://github.com/openssl/openssl/commit/ef2fb66ec571564d64d1c74a12e388a2a54d05d2
https://github.com/openssl/openssl/commit/eeee3cbd4d682095ed431052f00403004596373e
https://github.com/openssl/openssl/commit/7bbca05be55b129651d9df4bdb92becc45002c12
https://github.com/openssl/openssl/commit/572844beca95068394c916626a6d3a490f831a49
https://github.com/openssl/openssl/commit/2502e7b7d4c0cf4f972a881641fe09edc67aeec4