KCCMBlockCipher MAC does not bind nonce when AAD is absent (cross-nonce AEAD forgery)
Priority MEDIUM 43CWE-354Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · None
- Fix status
- Partial Red Hat: 1 fixed, 11 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat.
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00236 14th percentileScored 2026-11-07
Fix Partial BC-JAVA (Legion of the Bouncy Castle Inc.): 1.85BC-LTS-JAVA (Legion of the Bouncy Castle Inc.): 2.73.12Red Hat: 1 advisoryRed Hat: 1 fixed, 11 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Legion of the Bouncy Castle Inc. | BC-JAVA | before 1.85 | 1.85 | Patch available | CNA |
| Legion of the Bouncy Castle Inc. | BC-LTS-JAVA | 2.73.0 to before 2.73.12 | 2.73.12 | Patch available | CNA |
- BC-JAVA VendorLegion of the Bouncy Castle Inc. Affected before 1.85 Fixed in 1.85 Patch available CNA
- BC-LTS-JAVA VendorLegion of the Bouncy Castle Inc. Affected 2.73.0 to before 2.73.12 Fixed in 2.73.12 Patch available CNA
CPE configurations NVD · 2
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:bouncycastle:bc-java:*:*:*:*:*:*:*:* | before 1.85 | Vulnerable | Legion of the Bouncy Castle Inc. |
| cpe:2.3:a:bouncycastle:bouncy_castle_for_java_lts:*:*:*:*:*:*:*:* | up to 2.73.11 | Vulnerable | Legion of the Bouncy Castle Inc. |
- cpe:2.3:a:bouncycastle:bc-java:*:*:*:*:*:*:*:* Versions before 1.85 Vulnerable ·Legion of the Bouncy Castle Inc.
- cpe:2.3:a:bouncycastle:bouncy_castle_for_java_lts:*:*:*:*:*:*:*:* Versions up to 2.73.11 Vulnerable ·Legion of the Bouncy Castle Inc.
Remediation
- Fix · CNA BC-JAVA (Legion of the Bouncy Castle Inc.) Fixed in 1.85
- Fix · CNA BC-LTS-JAVA (Legion of the Bouncy Castle Inc.) Fixed in 2.73.12
Red Hat 1 advisory
- RHSA-2026:95887 Released 2026-11-06 · Red Hat rating ImportantRed Hat JBoss Enterprise Application Platform 8.1.9 security update
- Red Hat JBoss Enterprise Application Platform 8.1
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
Legion of the Bouncy Castle BC-JAVA 1.85
32 records Highest priority Priority MEDIUM 23 MEDIUM, 9 LOW
Other records, highest priority first
- TI-2026-42545 MTI/A0 DH agreement exponentiates unvalidated peer valuePriority MEDIUM 48
- TI-2026-42533 JSSE hostname verifier CN-fallback enabled by default despite documented opt-inPriority MEDIUM 48
- TI-2026-41816 Stapled OCSP response accepted without binding to the checked certificatePriority MEDIUM 48
- Release ·
Legion of the Bouncy Castle BC-LTS-JAVA 2.73.12
28 records Highest priority Priority MEDIUM 20 MEDIUM, 8 LOW
Other records, highest priority first
- TI-2026-42545 MTI/A0 DH agreement exponentiates unvalidated peer valuePriority MEDIUM 48
- TI-2026-42533 JSSE hostname verifier CN-fallback enabled by default despite documented opt-inPriority MEDIUM 48
- TI-2026-41816 Stapled OCSP response accepted without binding to the checked certificatePriority MEDIUM 48
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| OpenShift Developer Tools and Services | Affected | — |
| Red Hat AMQ Broker 7 | Affected | No fix yet |
| Red Hat Ansible Automation Platform 2 | Affected | — |
| Red Hat Build of Keycloak | Affected | No fix yet |
| Red Hat JBoss Enterprise Application Platform 7 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift AI (RHOAI) | Affected | — |
| Red Hat OpenShift Dev Spaces | Affected | — |
| Red Hat Satellite 6 | Affected | — |
| Red Hat Single Sign-On 7 | Affected | No fix planned: Out of support scope |
| Red Hat build of Apache Camel for Spring Boot 4 | Affected | No fix yet |
| Red Hat build of Apicurio Registry 3 | Affected | No fix yet |
| Red Hat JBoss Enterprise Application Platform 8.1 | Fixed | RHSA-2026:95887 |
Not affected: 4 products
- Red Hat Fuse 7
- Red Hat JBoss Enterprise Application Platform Expansion Pack
- Red Hat build of Apache Camel 4 for Quarkus 3
- Red Hat build of Quarkus
Timeline
- 2026-10-02 Threatist record created from CVE-2026-12803
- 2026-10-03 Alias added: GHSA-4r33-j73q-cw77
- 2026-11-06 Fix available: RHSA-2026:95887 · Red Hat
- 2026-11-06 Fix available: Red Hat JBoss Enterprise Application Platform 8.1 · Red Hat
References
More Legion of the Bouncy Castle Inc. Bc-java vulnerabilities
- TI-2018-15967 Legion of the Bouncy Castle Legion of the Bouncy Castle Java Cryptography APIs 1.58 up to… CVSS 3.1CRITICAL 9.8
- TI-2017-09736 BouncyCastle JCE TLS Bleichenbacher/ROBOT CVSS 3.0HIGH 7.5
- TI-2026-42545 MTI/A0 DH agreement exponentiates unvalidated peer value CVSS 4.0CRITICAL 9.3
- TI-2026-42533 JSSE hostname verifier CN-fallback enabled by default despite documented opt-in CVSS 4.0CRITICAL 9.3
- TI-2026-41816 Stapled OCSP response accepted without binding to the checked certificate CVSS 4.0CRITICAL 9.3
- TI-2026-07701 Name Constraints bypass via trailing dot in rfc822Name and URI CVSS 4.0CRITICAL 9.3
Sources
- CVE-2026-12803 · CVE Program
- CVE-2026-12803 · NVD
- FIRST EPSS
- GHSA-4r33-j73q-cw77 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-12803 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences