CVE-2026-12803

Summary

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 Software

VendorProductVersion RangeStatus
Legion of the Bouncy Castle Inc.BC-JAVA0 < 1.85affected
Legion of the Bouncy Castle Inc.BC-LTS-JAVA2.73.0 < 2.73.12affected

Weaknesses

  • CWE-354: CWE-354 Improper Validation of Integrity Check Value

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: yes
    • Technical Impact: partial

References