wolfSSL up to 5.9.0 DTLS heap-based overflow

Summaryinfo

A vulnerability was found in wolfSSL up to 5.9.0. It has been classified as critical. Affected is an unknown function of the component DTLS Handler. The manipulation leads to heap-based overflow. This vulnerability is referenced as CVE-2026-5264. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in wolfSSL up to 5.9.0. It has been rated as critical. This issue affects an unknown code block of the component DTLS Handler. The manipulation with an unknown input leads to a heap-based overflow vulnerability. Using CWE to declare the problem leads to CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Heap buffer overflow in DTLS 1.3 ACK message processing. A remote attacker can send a crafted DTLS 1.3 ACK message that triggers a heap buffer overflow.

The weakness was published by Sunwoo Lee. It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-5264 since 03/31/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 305887 (Linux Distros Unpatched Vulnerability : CVE-2026-5264), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.9.1 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (305887). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Name

• wolfSSL

Version

• 5.0
• 5.1
• 5.2
• 5.3
• 5.4
• 5.5
• 5.6
• 5.7
• 5.8
• 5.9.0

License

• open-source

Website

• Product: https://github.com/wolfssl/wolfssl/

CPE 2.3info

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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