Bouncy Castle Java CMS verifySignatures flaw (before 1.85/2.73.12/FIPS)
CVE-2026-59639 Published on August 3, 2026
CMS verifySignatures returns true for SignedData with zero signers
In Bouncy Castle for Java before 1.85, CMS verifySignatures returns true for SignedData with zero signers. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bcpkix-fips 1.0.12 (1.0.X series), 2.0.12 (2.0.X series) and 2.1.12 (2.1.X series).
Vulnerability Analysis
CVE-2026-59639 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
Improper Verification of Cryptographic Signature
The software does not verify, or incorrectly verifies, the cryptographic signature for data.
Affected Versions
Legion of the Bouncy Castle Inc. BC-JAVA:- Before 1.85 is affected.
- Version 2.73.0 and below 2.73.12 is affected.
- Version 1.0.0 and below 1.0.12 is affected.
- Version 2.0.0 and below 2.0.12 is affected.
- Version 2.1.0 and below 2.1.12 is affected.