Description
HMAC zero-length tag forgery in EVP_DigestVerifyFinal, where a zero-length tag could be accepted as valid during HMAC verification. In the OpenSSL-compatibility HMAC verify path the supplied signature length was only checked as not exceeding the MAC length, so a zero-length or otherwise truncated tag could pass verification. The fix requires the supplied tag length to exactly equal the MAC length and rejects a zero-length MAC, so a forged short or empty tag is no longer accepted.
Problem types
CWE-347 Improper Verification of Cryptographic Signature
Product status
3.15.5 (semver)
Credits
Nicholas Carlini from Anthropic
References
github.com/wolfSSL/wolfssl/pull/10192
www.wolfssl.com/docs/security-vulnerabilities/