CVE-2026-5588 PUBLISHED

PKIX draft CompositeVerifier accepts empty signature sequence as valid.

Assigner: bcorg
Reserved: 04.04.2026 Published: 15.04.2026 Updated: 15.04.2026

: Use of a Broken or Risky Cryptographic Algorithm vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA bcpkix on all (pkix modules).

PKIX draft CompositeVerifier accepts empty signature sequence as valid.

This issue affects BC-JAVA: from 1.49 before 1.84.

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
CVSS Score: 10

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	High	Confidentiality	High
Attack Complexity	Low	Integrity	High	Integrity	High
Attack Requirements	None	Availability	High	Availability	High
Privileges Required	None
User Interaction	None

CVSS 4.0

Vendor	Legion of the Bouncy Castle Inc.
Product	BC-JAVA
Versions	Default: unaffected affected from 1.49 to 1.84 (excl.)