CVE-2026-59639

High

Description

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).

SeverityHigh

CVSS7.5

Exploit probability—

ProductBouncycastle Bcpkix-fips

PublishedAug 3, 2026

First seenAug 3, 2026

Weakness typeCWE-347CWE-347

How to fix

Update

bouncycastle bcpkix-fips1.0.12, 2.0.12, 2.1.12 or later
bouncycastle bc-java1.85 or later

Patches

github.com/bcgit/bc-java/commit/99ddc6dcc6782e6a76b0dd587c77e62eb7096ad0

Vendor advisories

github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059639

Affected products

Product	Affected versions	Fixed in
bouncycastle bcpkix-fips	v < 1.0.12, 2.0.7 ≤ v < 2.0.12, 2.1.8 ≤ v < 2.1.12	1.0.12, 2.0.12, 2.1.12
bouncycastle bc-java	v < 1.85	1.85
bouncycastle bouncy_castle_for_java_lts	v ≤ 2.73.11	—

Check your version

Choose the product and enter the version you run to see whether it falls in the affected range.

In the Intelligence 360 plan

Attack Surface Management

See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.