Medium [CVE-2025-32988] vulnerability in gnutls othername san export

A flaw was found in GnuTLS. A double-free vulnerability exists in GnuTLS due to incorrect ownership handling in the export logic of Subject Alternative Name (SAN) entries containing an otherName.

If the type-id OID is invalid or malformed, GnuTLS will call asn1_delete_structure() on an ASN.1 node it does not own, leading to a double-free condition when the parent function or caller later attempts to free the same structure.

This vulnerability can be triggered using only public GnuTLS APIs and may result in denial of service or memory corruption, depending on allocator behavior.

This vulnerability is rated Moderate rather than Important because, although it involves a memory management flaw (double-free) that can potentially lead to memory corruption, practical exploitation is limited by modern memory protection mechanisms and contextual constraints.

The issue occurs only when processing malformed SAN otherName entries through public GnuTLS APIs—an uncommon and controlled code path in most deployments.

Furthermore, exploitation for arbitrary code execution is highly dependent on allocator behavior and requires precise heap manipulation, which is non-trivial under defenses such as Address Space Layout Randomization (ASLR), Data Execution Prevention (DEP), and hardened memory allocators.