{"schemaVersion":3,"id":"CVE-2026-103601","aliases":[],"status":"published","duplicateOf":null,"title":"CcmBlockCipher and KCcmBlockCipher leave unverified plaintext in the output buffer after a failed tag check","description":"Release of unverified plaintext in the CCM (CcmBlockCipher) and DSTU 7624 CCM (KCcmBlockCipher) AEAD modes in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote attacker to obtain decryptions of ciphertexts of their choosing via forged messages sent to an application that lets the output buffer of a failed decryption be observed, for example through buffer reuse or logging, because decryption wrote the recovered plaintext into the caller-supplied output buffer before checking the authentication tag and left it there when the check failed. Only decryption into a caller-supplied buffer is affected; methods that return a newly allocated array are not.","dates":{"published":"2026-10-02T07:09:17.064Z","modified":"2026-10-02T17:52:45.900Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":8.2,"severity":"high","version":"4.0","versionLabel":"v4.0","source":"CVE.org","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","computed":false,"selection":"backend-summary"},"metrics":[{"version":"4.0","versionLabel":"v4.0","source":"CVE.org","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","exploitability":null,"impact":null,"computed":false},{"version":"4.0","versionLabel":"v4.0","source":"NVD","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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00286,"percentile":0.19982,"severity":"low","asOf":"2026-10-22T00:00:00.000Z","change":{"pp":null,"baselineDate":null,"baselineScore":null},"history":[{"date":"2026-10-02T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-21T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-22T00:00:00.000Z","score":0.00286,"percentile":0.19982}],"last30":[{"date":"2026-10-02T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-21T00:00:00.000Z","score":0.00286,"percentile":null},{"date":"2026-10-22T00:00:00.000Z","score":0.00286,"percentile":0.19982}]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[{"id":"CWE-354","name":"Improper Validation of Integrity Check Value","description":"The product does not validate or incorrectly validates the integrity check values or \"checksums\" of a message. 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