{"schema":"threatline.record/2","record":{"id":"CVE-2026-63567","aliases":[],"summary":"IesEngine block-cipher mode checks padding before MAC (CBC padding oracle)","details":"Observable discrepancy in IesEngine.DecryptBlock in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote attacker who has captured an IES or ECIES ciphertext, and who can submit modified ciphertexts for decryption under the same key pair, to recover its plaintext via a CBC padding-oracle attack, because in block-cipher mode the engine decrypts the ciphertext and removes its padding before verifying the MAC. A padding failure is therefore reported with a different error message, and without the MAC computation, compared with a MAC failure. Only applications that construct IesEngine directly with a padded block cipher, such as AES in CBC mode with PKCS#7 padding, are affected; stream-mode IES is not.","categories":["Unclassified"],"product":"bc-csharp","vendor":"Legion of the Bouncy Castle Inc.","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-63567","source_modified_at":"2026-10-02T18:09:54.933Z","fetched_at":"2026-10-23T18:52:38.922436Z","product":"bc-csharp","vendor":"Legion of the Bouncy Castle Inc.","versions":[{"status":"affected","version":"0","lessThan":"2.7.0","versionType":"semver"}],"defaultStatus":"unaffected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-63567","source_modified_at":"2026-10-02T18:09:54.933Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"bc-csharp","ecosystem":null},"version":"2.7.0","basis":"first unaffected version stated in the CVE record"}],"cvss":8.2,"severity":"High","kev":{"listed":false},"epss":{"probability":0.00467,"percentile":0.39504,"score_date":"2026-10-23"},"published_at":"2026-10-02T06:58:32.487Z","modified_at":"2026-10-02T18:09:54.933Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-63567","fetched_at":"2026-10-23T18:52:38.922436Z","source_modified_at":"2026-10-02T18:09:54.933Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-63567","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63567","tags":["vendor-advisory"]},{"source":"CVE List","url":"https://github.com/bcgit/bc-csharp/commit/f881400b761134160ec2a05fd27c3e569453788d","tags":["patch"]},{"source":"CVE List","url":"https://github.com/bcgit/bc-csharp/commit/eaa42e1e8125b3e2e25e365c4194c7cd5932360b","tags":["patch"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"none","automatable":"no","technical_impact":"partial","assessed_at":"2026-10-02T18:09:42.725922Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":null,"confidence":"unknown","reviewed":false},"change_timestamp":"2026-10-02T18:09:54.933Z","content_hash":"d812776dd4d5ca88916ca816c1c02879781dbdab3246d7684bbfbd1c5189de3a"}}