# CVE-2026-12803

## Summary

- **CVE ID:** CVE-2026-12803
- **Severity:** HIGH
- **CVSS Score:** 8.7 (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)
- **CWE:** CWE-354
- **Published:** Aug 3, 2026
- **Last Modified:** Aug 3, 2026

## 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.

## Affected Products

- Legion of the Bouncy Castle Inc. — BC-JAVA (0)
- Legion of the Bouncy Castle Inc. — BC-LTS-JAVA (2.73.0)

## References

- [CNA](https://github.com/bcgit/bc-java/wiki/CVE-2026-12803)
- [CNA](https://github.com/bcgit/bc-java/commit/697794413ebf7bc5e3fce609a707826ba52981af)
- [CNA](https://github.com/bcgit/bc-java/commit/7d79aa76e984da85f2a541cae8ba2ae56e1713bc)
- [CNA](https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9012803)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.17%
- **EPSS Percentile:** 6.0

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._