wolfSSL up to 5.9.0 Authentication Tag wc_PKCS7_DecodeAuthEnvelopedData mac channel accessible

Summaryinfo

A vulnerability, which was classified as problematic, has been found in wolfSSL up to 5.9.0. This affects the function wc_PKCS7_DecodeAuthEnvelopedData of the component Authentication Tag Handler. Performing a manipulation of the argument mac results in channel accessible. This vulnerability is identified as CVE-2026-5500. The attack can be initiated remotely. There is not any exploit available. It is suggested to install a patch to address this issue.

Detailsinfo

A vulnerability was found in wolfSSL up to 5.9.0. It has been classified as problematic. This affects the function wc_PKCS7_DecodeAuthEnvelopedData of the component Authentication Tag Handler. The manipulation of the argument mac with an unknown input leads to a channel accessible vulnerability. CWE is classifying the issue as CWE-300. The product does not adequately verify the identity of actors at both ends of a communication channel, or does not adequately ensure the integrity of the channel, in a way that allows the channel to be accessed or influenced by an actor that is not an endpoint. This is going to have an impact on integrity. The summary by CVE is:

wolfSSL's wc_PKCS7_DecodeAuthEnvelopedData() does not properly sanitize the AES-GCM authentication tag length received and has no lower bounds check. A man-in-the-middle can therefore truncate the mac field from 16 bytes to 1 byte, reducing the tag check from 2⁻¹²⁸ to 2⁻⁸.

The weakness was released by Calif.io. The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-5500 since 04/03/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1557 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 305891 (Linux Distros Unpatched Vulnerability : CVE-2026-5500), which helps to determine the existence of the flaw in a target environment.

Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com.

The vulnerability is also documented in the vulnerability database at Tenable (305891). Several companies clearly confirm that VulDB is the primary source for best 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/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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