{"id":"CVE-2026-12803","summary":"KCCMBlockCipher MAC does not bind nonce when AAD is absent (cross-nonce AEAD forgery)","details":"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.","modified":"2026-09-04T08:11:48.776522Z","published":"2026-08-03T02:52:20.460Z","related":["SUSE-SU-2026:23127-1","SUSE-SU-2026:23150-1","SUSE-SU-2026:3559-1","openSUSE-SU-2026:11445-1","openSUSE-SU-2026:21538-1"],"database_specific":{"cna_assigner":"bcorg","cwe_ids":["CWE-354"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/12xxx/CVE-2026-12803.json"},"references":[{"type":"WEB","url":"https://www.bouncycastle.org/download/bouncy-castle-java-lts/"},{"type":"WEB","url":"https://www.bouncycastle.org/download/bouncy-castle-java/"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/12xxx/CVE-2026-12803.json"},{"type":"ADVISORY","url":"https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9012803"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-12803"},{"type":"FIX","url":"https://github.com/bcgit/bc-java/commit/697794413ebf7bc5e3fce609a707826ba52981af"},{"type":"FIX","url":"https://github.com/bcgit/bc-java/commit/7d79aa76e984da85f2a541cae8ba2ae56e1713bc"},{"type":"PACKAGE","url":"https://github.com/bcgit/bc-java"},{"type":"PACKAGE","url":"https://github.com/bcgit/bc-lts-java"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/bcgit/bc-java","events":[{"introduced":"0"},{"fixed":"57fbd3c501f7a369f64eda311d6a709fc0bcae84"},{"fixed":"697794413ebf7bc5e3fce609a707826ba52981af"},{"fixed":"7d79aa76e984da85f2a541cae8ba2ae56e1713bc"}],"database_specific":{"cpe":"cpe:2.3:a:bouncycastle:bc-java:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"1.85"}],"source":["CPE_RANGE","REFERENCES"]}},{"type":"GIT","repo":"https://github.com/bcgit/bc-lts-java","events":[{"introduced":"468b5082f3f0971e80bf9edb7029c17b39b9ba0c"},{"fixed":"f101b232c5d3e07ecdd504210a57e43831d6cd65"}],"database_specific":{"cpe":"cpe:2.3:a:bouncycastle:bouncy_castle_for_java_lts:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"2.73.0"},{"fixed":"2.73.12"},{"introduced":"0"},{"last_affected":"2.73.11"}],"source":["AFFECTED_FIELD","CPE_RANGE"]}}],"versions":["r1rv84","r1rv81","r1rv83","r1rv82","r1rv80","r1rv78","r1rv77","r1rv76","r1rv75","r1rv74","r1rv73","r2rv73dot11","r2rv73dot10","r2rv73dot9","r2rv73dot8","r2rv73dot6","r2rv73dot4","r2rv73dot3","r2rv73dot1","r2rv73dot0"],"database_specific":{"vanir_signatures":[{"target":{"file":"core/src/main/java/org/bouncycastle/crypto/modes/KCCMBlockCipher.java","function":"processAAD"},"deprecated":false,"digest":{"length":1338,"function_hash":"7859619620194799728679201341619350374"},"id":"CVE-2026-12803-23690617","signature_type":"Function","signature_version":"v1","source":"https://github.com/bcgit/bc-java/commit/697794413ebf7bc5e3fce609a707826ba52981af"},{"digest":{"function_hash":"330085538170321426461012785600519507132","length":1402},"id":"CVE-2026-12803-27bc2d79","signature_type":"Function","signature_version":"v1","source":"https://github.com/bcgit/bc-java/commit/7d79aa76e984da85f2a541cae8ba2ae56e1713bc","target":{"file":"core/src/main/java/org/bouncycastle/crypto/modes/KCCMBlockCipher.java","function":"processAAD"},"deprecated":false},{"target":{"function":"processPacket","file":"core/src/main/java/org/bouncycastle/crypto/modes/KCCMBlockCipher.java"},"deprecated":false,"digest":{"function_hash":"340073630505974547917171180437211506149","length":2065},"id":"CVE-2026-12803-2f11a1f4","signature_type":"Function","signature_version":"v1","source":"https://github.com/bcgit/bc-java/commit/697794413ebf7bc5e3fce609a707826ba52981af"},{"id":"CVE-2026-12803-30871725","signature_type":"Line","signature_version":"v1","source":"https://github.com/bcgit/bc-java/commit/697794413ebf7bc5e3fce609a707826ba52981af","target":{"file":"core/src/test/java/org/bouncycastle/crypto/test/DSTU7624Test.java"},"deprecated":false,"digest":{"line_hashes":["13241190153418575115211978528953783071","68773123159912188478289956958372014665","322200301024387533841575228653024502111","217107377075537363414838838465613957749","185475881173156544269873647740793641214","112282028145144829271635793220694313235","55786641628166949157166300556499813953"],"threshold":0.9}},{"deprecated":false,"digest":{"line_hashes":["134065995780806424909892687165476904093","32379593275394507583303084739714139578","182738848983206920801789042714789844374","118398943054389193871715295210865746096","185114929898326706304851151479918525530","61934423629945873161489042519064268954","192971688609491774569621224453823700652","177260572292465906947293309369155931873","185704606458653778969748534924673207144","50928869830128127230614395721960165771","97731694455897932065456692722602612637","108663769404296603634055449591317907553","271635530767887488951777148569267939355","138521971876497224070918519187332124313","57209399261966929721656171505350369018","258238453942738471281420413302517784075","115362414568935068296400945029314794447","159479292776671047309768922578181921431","227186833754185580460734264402319794366","2394005270841537529478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