CVE-2026-12803
published 2026-08-03CVE-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…
PriorityP342high7.5CVSS 3.1
AVNACLPRNUINSUCNIHAN
EPSS
0.20%
9.5th percentile
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
24 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| ansible-automation-platform-27 | de-minimal-rhel9 | — | — |
| ansible-automation-platform-27 | de-supported-rhel9 | — | — |
| bouncycastle | bc-java | < 1.85 | 1.85 |
| bouncycastle | bouncy_castle_for_java_lts | <= 2.73.11 | — |
| candlepinproject | candlepin | — | — |
| devspaces | jetbrains-ide-rhel9 | — | — |
| devspaces | openvsx-rhel9 | — | — |
| devspaces | pluginregistry-rhel9 | — | — |
| jboss-eap-7 | eap74-els-openjdk11-openshift-rhel8 | — | — |
| jboss-eap-7 | eap74-els-openjdk17-openshift-rhel8 | — | — |
| jboss-eap-7 | eap74-els-openjdk8-openshift-rhel8 | — | — |
| jenkins | jenkins | — | — |
| legion_of_the_bouncy_castle_inc | bc-java | < 1.85 | 1.85 |
| legion_of_the_bouncy_castle_inc | bc-lts-java | >= 2.73.0 < 2.73.12 | 2.73.12 |
| ocp-tools-4 | jenkins-rhel8 | — | — |
| ocp-tools-4 | jenkins-rhel9 | — | — |
| rhbk | keycloak-rhel9 | — | — |
| 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-cuda130-torch210-py312-rhel9 | — | — |
| rhoai | odh-th06-cuda130-torch291-py312-rhel9 | — | — |
| rhoai | odh-th06-rocm64-torch291-py312-rhel9 | — | — |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
nvdv4.08.7HIGHCVSS: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
vendor_redhat7.5HIGH
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Red Hat
org.bouncycastle/bc-java: Bouncy Castle for Java: Authenticated Encryption Forgery Vulnerability
vendor_redhat·2026-08-03·CVSS 7.5
CVE-2026-12803 [HIGH] CWE-347 org.bouncycastle/bc-java: Bouncy Castle for Java: Authenticated Encryption Forgery Vulnerability
org.bouncycastle/bc-java: Bouncy Castle for Java: Authenticated Encryption Forgery Vulnerability
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.
A flaw was found in Bouncy Castle for Java. The cryptographic module responsible for authenticated encryption does not correctly link a unique random value (nonce) with the message authentication code when no additional authenticated data is provided. This oversight could allow an attacker to forge encrypted messages, potentially compromising the integrity of sensitive information.
Statement: This is an Important vulnerability in Bouncy Castle for Java that could lead to authenticated encryption forger
VulDB
Legion of the Bouncy Castle Bouncy Castle for Java/Bouncy Castle for Java LTS prior 1.85/2.73.12 KCCMBlockCipher MAC signature verification (Nessus ID 331790 / WID-SEC-2026-2622)
vuldb·2026-09-03·CVSS 7.5
CVE-2026-12803 [HIGH] Legion of the Bouncy Castle Bouncy Castle for Java/Bouncy Castle for Java LTS prior 1.85/2.73.12 KCCMBlockCipher MAC signature verification (Nessus ID 331790 / WID-SEC-2026-2622)
A vulnerability labeled as problematic has been found in Legion of the Bouncy Castle Bouncy Castle for Java and Bouncy Castle for Java LTS. This affects an unknown part of the component KCCMBlockCipher MAC. Executing a manipulation can lead to improper verification of cryptographic signature.
This vulnerability is handled as CVE-2026-12803. The attack can be executed remotely. There is not any exploit available.
The affected component should be upgraded.
GHSA
In Bouncy Castle for Java before 1.85, KCCMBlockCipher MAC does not bind nonce when AAD is absent (cross-nonce AEAD forgery).
ghsa_unreviewed·2026-08-03
CVE-2026-12803 [HIGH] CWE-354 In Bouncy Castle for Java before 1.85, KCCMBlockCipher MAC does not bind nonce when AAD is absent (cross-nonce AEAD forgery).
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.
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2026-08-03
Published