CVE-2026-59639 PUBLISHED

CMS verifySignatures returns true for SignedData with zero signers

Assigner: bcorg
Reserved: 06.07.2026 Published: 03.08.2026 Updated: 03.08.2026

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).

Metrics

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/U:Amber
CVSS Score: 8.7

Product Status

Vendor Legion of the Bouncy Castle Inc.
Product BC-JAVA
Versions Default: unaffected
  • affected from 0 to 1.85 (excl.)
Vendor Legion of the Bouncy Castle Inc.
Product BC-LTS-JAVA
Versions Default: unaffected
  • affected from 2.73.0 to 2.73.12 (excl.)
Vendor Legion of the Bouncy Castle Inc.
Product BC-FJA
Versions Default: unaffected
  • affected from 1.0.0 to 1.0.12 (excl.)
  • affected from 2.0.0 to 2.0.12 (excl.)
  • affected from 2.1.0 to 2.1.12 (excl.)

Credits

  • Alex Gaynor in collaboration with Claude and Anthropic Research reporter

References

Problem Types

  • CWE-347 Improper Verification of Cryptographic Signature CWE