CVE-2026-12803

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.

Published 03 Aug 2026, 04:16 UTC Last modified 03 Aug 2026, 04:16 UTC

8.7

CVSS 4.0 HIGH base score

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber

Attack profile

The conditions required to exploit this vulnerability and its potential impact.

Attack vector Network

Attack complexity Low

Privileges required None

User interaction None

Scope Not assessed

Confidentiality Not assessed

Integrity Not assessed

Availability Not assessed

Affected products

Product applicability statements supplied with the NVD record.

NVD has not published structured affected-product data for this record.

Weakness classification

CWE categories help security teams group the underlying software weakness.

CWECWE-354

Source references

External advisories, patches and technical reports attached to this CVE record.

NVD National Vulnerability Database recordnvd.nist.gov 01 Technical reference 91579145-5d7b-4cc5-b925-a0262ff19630 02 Technical reference 91579145-5d7b-4cc5-b925-a0262ff19630 03 Technical reference 91579145-5d7b-4cc5-b925-a0262ff19630