{"schemaVersion":3,"id":"CVE-2026-20354","aliases":[],"status":"published","duplicateOf":null,"title":null,"description":"Multiple vulnerabilities in the Secure/Multipurpose Internet Mail Extensions (S/MIME) decryption functionality of Cisco Secure Email could allow an unauthenticated, remote attacker to recover plain text from encrypted email messages.\n\nThese vulnerabilities are due to insufficient validation of message integrity. An attacker could exploit these vulnerabilities by using a machine-in-the-middle technique to intercept and modify traffic between email gateways. A successful exploit could allow the attacker to obtain plaintext content from the encrypted communication.","dates":{"published":"2026-09-02T16:14:29.829Z","modified":"2026-09-02T17:58:58.074Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":5.9,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":5.9,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":5.9,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00161,"percentile":0.04847,"severity":"low","asOf":"2026-10-20T00:00:00.000Z","change":{"pp":0.01200000000000001,"baselineDate":"2026-09-20T00:00:00.000Z","baselineScore":0.00149},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.00149,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.00149,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.00149,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.00149,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.00149,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.00149,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00149,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00149,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00149,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00149,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00161,"percentile":0.04847}],"last30":[{"date":"2026-09-20T00:00:00.000Z","score":0.00149,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00149,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00149,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00149,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00161,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00161,"percentile":0.04847}]},"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. This may prevent it from detecting if the data has been modified or corrupted in transmission.","type":"weakness","status":"Draft","abstraction":"Base","likelihoodOfExploit":"Medium","url":"https://cwe.mitre.org/data/definitions/354.html"}],"affected":[{"vendor":"cisco","product":"cisco secure email","name":"Cisco Secure Email","label":"cisco secure email","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"14.0.0-698","noFixRecorded":false,"fixedIn":null},{"text":"13.5.1-277","noFixRecorded":false,"fixedIn":null},{"text":"13.0.0-392","noFixRecorded":false,"fixedIn":null},{"text":"14.2.0-620","noFixRecorded":false,"fixedIn":null},{"text":"13.0.5-007","noFixRecorded":false,"fixedIn":null},{"text":"13.5.4-038","noFixRecorded":false,"fixedIn":null},{"text":"14.2.1-020","noFixRecorded":false,"fixedIn":null},{"text":"14.3.0-032","noFixRecorded":false,"fixedIn":null},{"text":"15.0.0-104","noFixRecorded":false,"fixedIn":null},{"text":"15.0.1-030","noFixRecorded":false,"fixedIn":null},{"text":"15.5.0-048","noFixRecorded":false,"fixedIn":null},{"text":"15.5.1-055","noFixRecorded":false,"fixedIn":null},{"text":"15.5.2-018","noFixRecorded":false,"fixedIn":null},{"text":"16.0.0-050","noFixRecorded":false,"fixedIn":null},{"text":"15.0.3-002","noFixRecorded":false,"fixedIn":null},{"text":"16.0.0-054","noFixRecorded":false,"fixedIn":null},{"text":"15.5.3-022","noFixRecorded":false,"fixedIn":null},{"text":"16.0.1-017","noFixRecorded":false,"fixedIn":null},{"text":"15.5.4-012","noFixRecorded":false,"fixedIn":null},{"text":"16.0.4-016","noFixRecorded":false,"fixedIn":null},{"text":"15.0.5-016","noFixRecorded":false,"fixedIn":null},{"text":"16.0.2-112","noFixRecorded":false,"fixedIn":null},{"text":"16.0.3-044","noFixRecorded":false,"fixedIn":null},{"text":"16.5.0-780","noFixRecorded":false,"fixedIn":null}],"versionsText":"14.0.0-698 | 13.5.1-277 | 13.0.0-392 | 14.2.0-620 | 13.0.5-007 | 13.5.4-038 | 14.2.1-020 | 14.3.0-032 | 15.0.0-104 | 15.0.1-030 | 15.5.0-048 | 15.5.1-055 | 15.5.2-018 | 16.0.0-050 | 15.0.3-002 | 16.0.0-054 | 15.5.3-022 | 16.0.1-017 | 15.5.4-012 | 16.0.4-016 | 15.0.5-016 | 16.0.2-112 | 16.0.3-044 | 16.5.0-780","eol":null,"hubHref":"/vendor/cisco/cisco_secure_email"}],"affectedCount":1,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-smime-disc-dzw4rEdY","label":"sec.cloudapps.cisco.com/security/…","hostname":"sec.cloudapps.cisco.com","tags":[]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2026-09-02T16:14:29.829Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2026-09-02T17:58:58.074Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":24,"level":"low","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-21T12:49:50.315Z","stale":false,"partial":false}}