CVE-2026-59639
Description
A flaw was found in Bouncy Castle for Java. The library's Cryptographic Message Syntax (CMS) component, which handles digital signature verification, incorrectly validates data that has no signers. This means that even if data is not digitally signed, the system might still consider it legitimate. This could allow an attacker to bypass critical security checks and potentially introduce unauthorized or malicious content.
Statement
Bouncy Castle for Java is bundled as a cryptographic provider across numerous Red Hat products. The CMS verifySignatures method incorrectly returns true for SignedData containing zero signers, so unsigned content may be treated as validly signed — a cryptographic signature-verification bypass with a high integrity impact. This affects applications that rely on Bouncy Castle CMS to verify signatures.
Mitigation
Red Hat is not aware of a mitigation for this flaw other than updating the affected Bouncy Castle component to a fixed version (bc-java 1.85, LTS 2.73.12, or BC-FJA bcpkix-fips 1.0.12/2.0.12/2.1.12) once available for the affected product.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | 7.5 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Understanding the Weakness (CWE)
Access Control,Integrity,Confidentiality
Technical Impact: Gain Privileges or Assume Identity; Modify Application Data; Execute Unauthorized Code or Commands
An attacker could gain access to sensitive data and possibly execute unauthorized code.
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