CVE-2025-69420

Issue summary: A type confusion vulnerability exists in the TimeStamp Response

verification code where an ASN1_TYPE union member is accessed without first

validating the type, causing an invalid or NULL pointer dereference when

processing a malformed TimeStamp Response file.

Impact summary: An application calling TSRESPverify_response() with a

malformed TimeStamp Response can be caused to dereference an invalid or

NULL pointer when reading, resulting in a Denial of Service.

The functions osslessgetsigningcert() and osslessgetsigningcert_v2()

access the signing cert attribute value without validating its type.

When the type is not VASN1SEQUENCE, this results in accessing invalid memory

through the ASN1_TYPE union, causing a crash.

Exploiting this vulnerability requires an attacker to provide a malformed

TimeStamp Response to an application that verifies timestamp responses. The

TimeStamp protocol (RFC 3161) is not widely used and the impact of the

exploit is just a Denial of Service. 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 TimeStamp Response 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.