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Fencer Vulns
high 7.5

CVE-2026-12803 json

KCCMBlockCipher MAC does not bind nonce when AAD is absent (cross-nonce AEAD forgery)

published 2026-08-03 3 mo ago modified 2026-09-02 2 mo ago also EUVD-2026-52134

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 14%
public exploits
0
none known

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.

Patch / fix

  • Legion of the Bouncy Castle Inc. BC-JAVA 1.85
  • Legion of the Bouncy Castle Inc. BC-LTS-JAVA 2.73.12
  • bouncycastle Debian 14 1.86-1

debian advisories DEBIAN-CVE-2026-12803

  • bouncycastle SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 1.85-150200.3.38.1
  • bouncycastle SLES 16.0, SLES for SAP applications 16.0 1.85-160000.1.1

suse advisories SUSE-SU-2026:3559-1SUSE-SU-2026:23127-1SUSE-SU-2026:23150-1

  • bouncycastle openSUSE Leap 16.0 1.85-160000.1.1
  • bouncycastle openSUSE Tumbleweed 1.85-1.1

opensuse advisories openSUSE-SU-2026:21538-1openSUSE-SU-2026:11445-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-12803 updated cvss 7.5

org.bouncycastle/bc-java: Bouncy Castle for Java: Authenticated Encryption Forgery Vulnerability

  • Red Hat AMQ Broker 7 bcprov-jdk18on Red Hat build of Apache Camel for Spring Boot 4 bcprov-jdk18on Red Hat build of Apicurio Registry 3 bcprov-jdk18on Red Hat Build of Keycloak bcprov-jdk18on, rhbk/keycloak-rhel9
    affected: workaround, no fix available
  • Red Hat JBoss Enterprise Application Platform 7 bcprov-jdk18on, jboss-eap-7/eap74-els-openjdk8-openshift-rhel8, jboss-eap-7/eap74-els-openjdk11-openshift-rhel8, jboss-eap-7/eap74-els-openjdk17-openshift-rhel8
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat Single Sign-On 7 bcprov-jdk18on
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat OpenShift Developer Tools and Services jenkins, jenkins-2-plugins, ocp-tools-4/jenkins-rhel8, ocp-tools-4/jenkins-rhel9 Red Hat Ansible Automation Platform 2 ansible-automation-platform-27/de-minimal-rhel9, ansible-automation-platform-27/de-supported-rhel9 Red Hat OpenShift AI (RHOAI) rhoai/odh-modelmesh-rhel9, rhoai/odh-spark-operator-rhel9, rhoai/odh-th06-cpu-torch210-py312-rhel9, rhoai/odh-th06-cpu-torch291-py312-rhel9, rhoai/odh-th06-rocm64-torch291-py312-rhel9, rhoai/odh-th06-cuda130-torch210-py312-rhel9, +1 more Red Hat OpenShift Dev Spaces devspaces/openvsx-rhel9, devspaces/jetbrains-ide-rhel9, devspaces/pluginregistry-rhel9 Red Hat Satellite 6 candlepin, candlepin-selinux
    under investigation
  • Red Hat JBoss Enterprise Application Platform 8.1
    fixed: vendor fix RHSA-2026:95887
  • Red Hat build of Apache Camel 4 for Quarkus 3 bcprov-jdk18on Red Hat build of Quarkus bcprov-jdk18on
    not affected: vulnerable code not present
  • Red Hat Fuse 7 bcprov-jdk18on Red Hat JBoss Enterprise Application Platform Expansion Pack bcprov-jdk18on
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 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
CNA 4.0 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/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
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected products

  • Legion of the Bouncy Castle Inc. BC-JAVA
  • Legion of the Bouncy Castle Inc. BC-LTS-JAVA

Classification

Weakness
  • CWE-354 Improper Validation of Integrity Check Value

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.