CVE-2026-12803

EUVD-2026-52134
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
7.5 HIGH
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 6.1%
Affected Products (NVD)
VendorProductVersion
bouncycastlebc-java
𝑥
< 1.85
bouncycastlebouncy_castle_for_java_lts
𝑥
≤ 2.73.11
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
bouncycastle
bookworm
vulnerable
forky
vulnerable
sid
vulnerable
trixie
vulnerable
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
bouncycastle
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
resolute
needs-triage
xenial
needs-triage
Amazon Linux logo
Amazon Linux Releases
Amazon Package
Release
bouncycastle
Amazon Linux 2023
0:1.70-4.amzn2023.0.8
fixed
bouncycastle-javadoc
Amazon Linux 2023
0:1.70-4.amzn2023.0.8
fixed
bouncycastle-mail
Amazon Linux 2023
0:1.70-4.amzn2023.0.8
fixed
bouncycastle-pg
Amazon Linux 2023
0:1.70-4.amzn2023.0.8
fixed
bouncycastle-pkix
Amazon Linux 2023
0:1.70-4.amzn2023.0.8
fixed
bouncycastle-tls
Amazon Linux 2023
0:1.70-4.amzn2023.0.8
fixed
bouncycastle-util
Amazon Linux 2023
0:1.70-4.amzn2023.0.8
fixed
Common Weakness Enumeration
Vulnerability Media Exposure
References
https://github.com/bcgit/bc-java/commit/697794413ebf7bc5e3fce609a707826ba52981af
https://github.com/bcgit/bc-java/commit/7d79aa76e984da85f2a541cae8ba2ae56e1713bc
https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9012803