CVE-2025-32988 in GnuTLS
Summary
by MITRE • 07/10/2025
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.
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Analysis
by VulDB Data Team • 11/28/2025
The vulnerability identified as CVE-2025-32988 represents a critical double-free condition within the GnuTLS cryptographic library that stems from improper memory management during ASN.1 structure handling. This flaw specifically manifests when processing Subject Alternative Name entries containing otherName types, where the library fails to maintain proper ownership semantics for ASN.1 nodes during the export process. The issue resides in the cryptographic library's handling of malformed or invalid type-id OIDs, creating a scenario where the library attempts to free memory it does not actually own, leading to the double-free condition when the original structure is later freed by the calling function.
From a technical perspective, this vulnerability operates at the intersection of memory management and ASN.1 parsing within cryptographic libraries, with the flaw classified under CWE-415 as double-free vulnerability. The root cause involves incorrect ownership tracking in the export logic where GnuTLS maintains references to ASN.1 nodes that it does not own, violating fundamental memory safety principles. When the type-id OID is malformed or invalid, the library executes asn1_delete_structure() on a node that has already been freed or is managed by a different memory allocator, resulting in undefined behavior. This condition can be triggered through public GnuTLS APIs without requiring special privileges or access, making it particularly concerning for widespread exploitation.
The operational impact of this vulnerability extends beyond simple denial of service to encompass potential memory corruption scenarios that could be exploited for more sophisticated attacks. Depending on the underlying memory allocator implementation and system configuration, attackers could potentially leverage this double-free condition to achieve arbitrary code execution or cause system instability. The vulnerability affects systems that rely on GnuTLS for secure communications, particularly those handling certificates with Subject Alternative Name entries containing otherName types, which are commonly found in enterprise environments and certificate authorities. The attack surface is broad as any application using GnuTLS for TLS/SSL connections and certificate processing could be impacted, including web servers, email servers, and network security appliances.
Mitigation strategies for CVE-2025-32988 should prioritize immediate patching of affected GnuTLS versions, with system administrators monitoring for security updates from their distribution vendors. Organizations should also implement network segmentation and monitoring to detect potential exploitation attempts, particularly focusing on certificate processing activities and TLS connection failures. The vulnerability demonstrates the critical importance of proper memory ownership management in cryptographic libraries and underscores the need for comprehensive testing of edge cases in ASN.1 parsing logic. Security teams should conduct thorough vulnerability assessments of systems using GnuTLS, particularly those handling certificate validation and secure communications, while also considering the broader implications for the software supply chain given GnuTLS's widespread adoption across various platforms and applications. This vulnerability aligns with ATT&CK technique T1059.007 for execution through system binaries and T1499.004 for denial of service, highlighting both the immediate operational impact and potential for escalation within compromised environments.