Vulnerability in Bouncycastle Bc-Java
CVE-2026-59639
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).
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.002 (15.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 15th percentile — 15.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Bouncycastle Bc-Java
- Bouncycastle Bcpkix-Fips
- Bouncycastle Bouncy Castle For Java Lts
- Legion Of The Bouncy Castle Inc. Bc-Fja — versions 1.0.0, 2.0.0, 2.1.0
- Legion Of The Bouncy Castle Inc. Bc-Java — versions 0
- Legion Of The Bouncy Castle Inc. Bc-Lts-Java — versions 2.73.0
Weakness classification (CWE)
References
- 91579145-5d7b-4cc5-b925-a0262ff19630 (Patch, patch)
- 91579145-5d7b-4cc5-b925-a0262ff19630 (vendor-advisory)
- 91579145-5d7b-4cc5-b925-a0262ff19630 (vendor-advisory, Third Party Advisory)
Frequently asked questions
- What is CVE-2026-59639?
- CVE-2026-59639 is a high-severity vulnerability in Bouncycastle Bc-Java, classified under Improper Verification of Cryptographic Signature. CVSS score: 7.5/10. Published 2026-08-03.
- How severe is CVE-2026-59639?
- High severity. CVSS v3 base score is 7.5 out of 10.