KCCMBlockCipher MAC does not bind nonce when AAD is absent (cross-nonce AEAD forgery) (Legion of the Bouncy Castle Inc. BC-JAVA)

CVE-2026-12803
HIGH 8.7

At a glance

Source
NVD
EPSS
EPSS 0.24 % · percentile 15 ()
State
PUBLISHED
Published
Updated
Assigner
bcorg
NVD status
Analyzed

Description

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.

Weaknesses (CWE)

  • CWE-354 — Improper Validation of Integrity Check Value

References

Scores

VersionScoreVectorScored by
CVSS 4.0HIGH 8.7CVSS: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:Amberbcorg
CVSS 4.0HIGH 8.7CVSS: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:AmberNVD · 91579145-5d7b-4cc5-b925-a0262ff19630 (Secondary)
CVSS 3.1HIGH 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:NNVD · nvd@nist.gov (Primary)

European references

CERT-FR advisories

Affected configurations (NVD CPE)

Affected products

ProductVersions
Legion of the Bouncy Castle Inc. · BC-JAVAaffected 0 < 1.85
Legion of the Bouncy Castle Inc. · BC-LTS-JAVAaffected 2.73.0 < 2.73.12

Sources

SourceLicence
CVE List (CVEProject cvelistV5)CVE Program Terms of Use
EPSS (FIRST.org)FIRST — attribution requested
ENISA EUVDENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feedsPublic domain — this product uses data from the NVD API but is not endorsed or certified by the NVD