GnuTLS libtasn1 up to 4.20.0 asn1_expend_octet_string buffer overflow

Summaryinfo

A vulnerability was found in GnuTLS libtasn1 up to 4.20.0. It has been declared as critical. This affects the function asn1_expend_octet_string. Such manipulation leads to buffer overflow. This vulnerability is listed as CVE-2025-13151. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability, which was classified as critical, has been found in GnuTLS libtasn1 up to 4.20.0. Affected by this issue is the function asn1_expend_octet_string. The manipulation with an unknown input leads to a buffer overflow vulnerability. Using CWE to declare the problem leads to CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Stack-based buffer overflow in libtasn1 version: v4.20.0. The function fails to validate the size of input data resulting in a buffer overflow in asn1_expend_octet_string.

The weakness was presented by Benny Zelster. This vulnerability is handled as CVE-2025-13151 since 11/13/2025. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 03/16/2026).

The vulnerability scanner Nessus provides a plugin with the ID 282447 (Linux Distros Unpatched Vulnerability : CVE-2025-13151), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the databases at Tenable (282447), EUVD (EUVD-2025-206262) and CERT Bund (WID-SEC-2026-0044). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

• Amazon Linux 2
• Fedora Linux
• Ubuntu Linux
• SUSE Linux
• SUSE openSUSE
• Open Source libtasn1

Productinfo

Type

• Network Encryption Software

Vendor

• GnuTLS

Name

• libtasn1

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7
• 4.8
• 4.9
• 4.10
• 4.11
• 4.12
• 4.13
• 4.14
• 4.15
• 4.16
• 4.17
• 4.18
• 4.19
• 4.20.0

License

• open-source

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Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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