{"id":"CVE-2026-63567","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-63567","generatedAt":"2026-10-28T04:41:05.221Z","title":"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…","description":"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.","published":"2026-10-02T07:16:37.000Z","lastModified":"2026-10-27T16:20:43.000Z","status":"Analyzed","sourceIdentifier":"91579145-5d7b-4cc5-b925-a0262ff19630","cvss":{"version":"4.0","score":8.2,"severity":"HIGH","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/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/M"},"cwe":["CWE-203"],"affected":["bouncycastle/bc-csharp"],"epss":{"score":0.00467,"percentile":0.40263,"date":"2026-10-27","history":[{"date":"2026-10-02","score":0.00467,"percentile":0.38202}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.47%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-02T07:16:37.000Z","detail":{"score":"8.2","severity":"HIGH","publishedAt":"2026-10-02T07:16:37.127Z"},"summary":"New CVE, high severity (CVSS 8.2)."}],"references":[{"url":"https://github.com/bcgit/bc-csharp/commit/eaa42e1e8125b3e2e25e365c4194c7cd5932360b","tags":["Patch"],"source":"91579145-5d7b-4cc5-b925-a0262ff19630"},{"url":"https://github.com/bcgit/bc-csharp/commit/f881400b761134160ec2a05fd27c3e569453788d","tags":["Patch"],"source":"91579145-5d7b-4cc5-b925-a0262ff19630"},{"url":"https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63567","tags":["Patch","Vendor Advisory"],"source":"91579145-5d7b-4cc5-b925-a0262ff19630"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-63567","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}