CVE-2026-55961: wolfSSL_PKCS7_verify() reports success for degenerate (certs-only) PKCS#7 with no signer

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-25 · updated 2026-06-26
Weakness: CWE-347

Description

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.

Affected products

wolfSSL: from 3.15.7 before 5.9.2 — fixed in 5.9.2

How to fix

Upgrade to a fixed version: wolfSSL 5.9.2. Check the vendor advisory for mitigations.

References

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