{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-12803", "assignerOrgId": "91579145-5d7b-4cc5-b925-a0262ff19630", "state": "PUBLISHED", "assignerShortName": "bcorg", "dateReserved": "2026-06-21T01:50:45.847Z", "datePublished": "2026-08-03T02:52:20.460Z", "dateUpdated": "2026-08-03T05:58:49.795Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "91579145-5d7b-4cc5-b925-a0262ff19630", "shortName": "bcorg", "dateUpdated": "2026-08-03T05:58:49.795Z"}, "title": "KCCMBlockCipher MAC does not bind nonce when AAD is absent (cross-nonce AEAD forgery)", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-354", "description": "CWE-354 Improper Validation of Integrity Check Value", "type": "CWE"}]}], "affected": [{"vendor": "Legion of the Bouncy Castle Inc.", "product": "BC-JAVA", "platforms": ["all"], "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java/", "packageName": "bcprov", "repo": "https://github.com/bcgit/bc-java", "packageURL": "pkg:maven/org.bouncycastle/bcprov-jdk18on", "modules": ["core"], "programFiles": ["KCCMBlockCipher"], "versions": [{"status": "affected", "version": "0", "lessThan": "1.85", "versionType": "maven"}], "defaultStatus": "unaffected"}, {"vendor": "Legion of the Bouncy Castle Inc.", "product": "BC-LTS-JAVA", "platforms": ["all"], "collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java-lts/", "packageName": "bcprov-lts8on", "repo": "https://github.com/bcgit/bc-lts-java", "packageURL": "pkg:maven/org.bouncycastle/bcprov-lts8on", "modules": ["core"], "programFiles": ["KCCMBlockCipher"], "versions": [{"status": "affected", "version": "2.73.0", "lessThan": "2.73.12", "versionType": "maven"}], "defaultStatus": "unaffected"}], "descriptions": [{"lang": "en", "value": "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.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>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.</p>"}]}], "references": [{"url": "https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9012803", "tags": ["vendor-advisory"]}, {"url": "https://github.com/bcgit/bc-java/commit/697794413ebf7bc5e3fce609a707826ba52981af", "tags": ["patch"]}, {"url": "https://github.com/bcgit/bc-java/commit/7d79aa76e984da85f2a541cae8ba2ae56e1713bc", "tags": ["patch"]}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "subConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "AMBER", "version": "4.0", "baseSeverity": "HIGH", "baseScore": 8.7, "vectorString": "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"}}], "credits": [{"lang": "en", "value": "Alex Gaynor in collaboration with Claude and Anthropic Research", "type": "reporter"}], "source": {"discovery": "UNKNOWN"}, "x_generator": {"engine": "bc release-notes template"}}}}

{}

{}

{}

{"created": "2026-08-03T09:00:15.057801+00:00", "updated": "2026-08-03T09:00:15.057808+00:00", "vendors": []}