CVE-2026-59639CWE-347

CVE-2026-59639

High · published August 3, 2026

CVSS v3.1

7.5

EPSS

Percentile

14.5

In the wild

Unconfirmed

What it is

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).

The record

Technical detail

CVSS v3.1: 7.5 · HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CVSS v4.0: Not supplied
EPSS: 0.00242 · 14.5th percentile
Weakness: CWE-347 · Improper Verification of Cryptographic Signature
Published: 2026-08-03T05:16Z

Affected products (5)

Product	Versions	Fixed in
bouncycastle/bc-java	< 1.85	1.85
bouncycastle/bcpkix-fips	< 1.0.12	1.0.12
bouncycastle/bcpkix-fips	≥ 2.0.7, < 2.0.12	2.0.12
bouncycastle/bcpkix-fips	≥ 2.1.8, < 2.1.12	2.1.12
bouncycastle/bouncy_castle_for_java_lts	≤ 2.73.11	—

References (2)

https://github.com/bcgit/bc-java/commit/99ddc6dcc6782e6a76b0dd587c77e62eb7096ad0 · 91579145-5d7b-4cc5-b925-a0262ff19630 https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059639 · 91579145-5d7b-4cc5-b925-a0262ff19630

EPSS history

Timeline

03 AUG 00:56Z
CMS verifySignatures returns true for SignedData with zero signers
cvelistv5