In Bouncy Castle for Java before 1.85, KCCMBlockCipher MAC does not bind nonce when AAD is absent (cross-nonce AEAD forgery). This issue also affects Bouncy Castle for Java LTS before 2.73.12.

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Bc-lts-java Subscribe
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Fixes

Solution

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Workaround

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History

Mon, 03 Aug 2026 16:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

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


Mon, 03 Aug 2026 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-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-java
Legion Of The Bouncy Castle Inc. bc-lts-java

Mon, 03 Aug 2026 06:45:00 +0000


Mon, 03 Aug 2026 04:00:00 +0000

Type Values Removed Values Added
Description In Bouncy Castle for Java before 1.85, KCCMBlockCipher MAC does not bind nonce when AAD is absent (cross-nonce AEAD forgery). This issue also affects Bouncy Castle for Java LTS before 2.73.12.
Title KCCMBlockCipher MAC does not bind nonce when AAD is absent (cross-nonce AEAD forgery)
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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: bcorg

Published:

Updated: 2026-08-03T15:22:55.531Z

Reserved: 2026-06-21T01:50:45.847Z

Link: CVE-2026-12803

cve-icon Vulnrichment

Updated: 2026-08-03T15:22:49.896Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-03T15:52:09Z

Weaknesses