Description
In Bouncy Castle for Java before 1.85, CMS AuthenticatedData content not bound to MAC when authAttrs present. 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: 2026-08-03
Score: 8.7 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

In Bouncy Castle libraries for Java, the CMS AuthenticatedData formatter fails to include the content in the Message Authentication Code when authentication attributes are present. This flaw allows an attacker to alter authenticated data without causing MAC verification failure, effectively bypassing integrity checks and enabling data tampering or forging of authenticated messages.

Affected Systems

Legion of the Bouncy Castle Inc. products are affected: Bouncy Castle for Java (BC-JAVA) prior to version 1.85, Bouncy Castle for Java LTS (BC-LTS-JAVA) prior to 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) prior to bcpkix-fips 1.0.12, 2.0.12, and 2.1.12.

Risk and Exploitability

The vulnerability carries a CVSS score of 8.7, indicating a high severity for integrity loss. EPSS data is not available, and the issue is not listed in the CISA KEV catalog. Exploitation would require that an attacker can supply or modify CMS AuthenticatedData objects processed by the affected library, which could happen in applications that perform cryptographic signing or authentication. Because the MAC is not bound to the content, forged or tampered messages may be authenticated successfully, leading to potential loss of data integrity and reliance on compromised data.

Generated by OpenCVE AI on August 4, 2026 at 10:55 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Upgrade all Bouncy Castle for Java libraries to the latest available versions: BC-JAVA 1.85 or newer, BC-LTS-JAVA 2.73.12 or newer, and BC-FJA to bcpkix-fips 1.0.12, 2.0.12, or 2.1.12 and later.
  • Audit and modify any application code that constructs or verifies CMS AuthenticatedData to ensure it uses the updated library and that the MAC calculation correctly includes the content; verify that all dependent libraries are also updated.
  • If immediate upgrade is not feasible, restrict the acceptance of CMS AuthenticatedData objects to trusted internal sources only, disable or reject authentication attributes in legacy code, and monitor for anomalous message modifications.

Generated by OpenCVE AI on August 4, 2026 at 10:55 UTC.

Tracking

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Advisories

No advisories yet.

History

Mon, 03 Aug 2026 16:15:00 +0000

Type Values Removed Values Added
First Time appeared Legion Of The Bouncy Castle Inc.
Legion Of The Bouncy Castle Inc. bc-fja
Legion Of The Bouncy Castle Inc. bc-java
Legion Of The Bouncy Castle Inc. bc-lts-java
Vendors & Products Legion Of The Bouncy Castle Inc.
Legion Of The Bouncy Castle Inc. bc-fja
Legion Of The Bouncy Castle Inc. bc-java
Legion Of The Bouncy Castle Inc. bc-lts-java

Mon, 03 Aug 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Mon, 03 Aug 2026 05:30:00 +0000

Type Values Removed Values Added
References

Mon, 03 Aug 2026 01:15:00 +0000

Type Values Removed Values Added
Description In Bouncy Castle for Java before 1.85, CMS AuthenticatedData content not bound to MAC when authAttrs present. 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).
Title CMS AuthenticatedData content not bound to MAC when authAttrs present
Weaknesses CWE-354
References
Metrics cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/U:Amber'}

Subscriptions

Legion Of The Bouncy Castle Inc. Bc-fja Bc-java Bc-lts-java
cve-icon MITRE

Status: PUBLISHED

Assigner: bcorg

Published:

Updated: 2026-08-03T13:27:19.619Z

Reserved: 2026-07-06T06:58:29.263Z

Link: CVE-2026-59642

cve-icon Vulnrichment

Updated: 2026-08-03T13:27:15.568Z

cve-icon NVD

Status : Undergoing Analysis

Published: 2026-08-03T01:16:44.203

Modified: 2026-08-04T14:50:12.360

Link: CVE-2026-59642

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-04T11:00:07Z

Weaknesses
  • CWE-354

    Improper Validation of Integrity Check Value