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.
History

Wed, 02 Sep 2026 10:45:00 +0000

Type Values Removed Values Added
First Time appeared Bouncycastle
Bouncycastle bc-java
Bouncycastle bouncy Castle For Java Lts
CPEs cpe:2.3:a:bouncycastle:bc-java:*:*:*:*:*:*:*:*
cpe:2.3:a:bouncycastle:bouncy_castle_for_java_lts:*:*:*:*:*:*:*:*
Vendors & Products Bouncycastle
Bouncycastle bc-java
Bouncycastle bouncy Castle For Java Lts
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N'}


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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: bcorg

Published: 2026-08-03T02:52:20.460Z

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

Status : Analyzed

Published: 2026-08-03T04:16:39.177

Modified: 2026-09-02T14:37:53.583

Link: CVE-2026-12803

cve-icon Redhat

No data.