CVE-2026-12860

A flaw was found in Bouncy Castle for Java. During the RSA PKCS#1 verification process, the last two hash bytes are incorrectly skipped when a NULL-omitted path is utilized. This vulnerability could allow an attacker to bypass cryptographic signature verification, potentially leading to the acceptance of forged or malicious data as authentic.

A signature verification flaw was found in Bouncy Castle for Java's RSA PKCS#1 parser (bcprov). When verifying RSA PKCS#1 v1.5 signatures utilizing a NULL-omitted DigestInfo path, the verification routine incorrectly skips the last two bytes of the expected digest hash. An unauthenticated remote attacker can exploit this truncated comparison to craft forged signatures that pass verification, bypassing cryptographic integrity controls.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Enforce strict DigestInfo encoding checks requiring explicit ASN.1 NULL parameters in RSA PKCS#1 v1.5 signature verification, or mandate the use of RSA-PSS signature schemes in application TLS/crypto configuration.