wolfSSL up to 5.9.1 Certificate Chain wolfSSL_PKCS7_verify signature verification

Summaryinfo

A vulnerability, which was classified as problematic, has been found in wolfSSL up to 5.9.1. This affects the function wolfSSL_PKCS7_verify of the component Certificate Chain Handler. This manipulation causes signature verification. The identification of this vulnerability is CVE-2026-55961. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as problematic was found in wolfSSL up to 5.9.1. Affected by this vulnerability is the function wolfSSL_PKCS7_verify of the component Certificate Chain Handler. The manipulation with an unknown input leads to a signature verification vulnerability. The CWE definition for the vulnerability is CWE-347. The product does not verify, or incorrectly verifies, the cryptographic signature for data. As an impact it is known to affect integrity. The summary by CVE is:

wolfSSL_PKCS7_verify() returning success for a degenerate (certs-only) PKCS#7 object that contains no signer. Such an object has empty signerInfos, so the underlying signed-data verification succeeds without authenticating any content. The compatibility-layer verify path now rejects the object when no signer signature has actually been verified, so a PKCS#7 carrying no valid signature is no longer reported as verified. This is enforced regardless of the PKCS7_NOVERIFY flag, which only suppresses signer certificate chain validation and was never intended to waive the requirement that a signature exist. Only affects OpenSSL compatibility builds that call the PKCS7_verify() compatibility API on potentially degenerate PKCS#7 bundles.

The weakness was shared by Nvidia Project Vanessa. The advisory is shared at github.com. This vulnerability is known as CVE-2026-55961 since 06/18/2026. The exploitation appears to be difficult. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 06/25/2026).

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

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

Productinfo

Name

• wolfSSL

Version

• 5.9.0
• 5.9.1

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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