{"id":"CVE-2025-66376","aliases":["EUVD-2026-0850","GHSA-h7wg-85fj-3c6g"],"status":"published","title":"Zimbra Collaboration (ZCS) 10 before 10.0.18 and 10.1 before 10.1.13 allows Classic UI stored XSS...","description":"Zimbra Collaboration (ZCS) 10 before 10.0.18 and 10.1 before 10.1.13 allows Classic UI stored XSS via Cascading Style Sheets (CSS) @import directives in an HTML e-mail message.","severity":{"version":"3.1","score":7.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.20227,"percentile":0.975,"model":"v2026.06.15"},"facts":{"in_kev":true,"known_exploited":true,"public_exploit":false,"fix_available":false},"cwes":["CWE-79"],"published":"2026-01-05T00:00:00Z","modified":"2026-10-28T02:30:45Z","kev":{"date_added":"2026-03-18","due_date":"2026-04-01","required_action":"Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","known_ransomware_use":"Unknown"},"exploitation":[{"source":"euvd","since":"2026-03-18"},{"source":"kev","since":"2026-03-18"}],"products":[{"vendor":"synacor","product":"zimbra collaboration suite (zcs)"},{"vendor":"synacor","product":"zimbra_collaboration_suite"},{"vendor":"zimbra","product":"collaboration"}],"references":[{"url":"https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories","tags":["Vendor Advisory","web"]},{"url":"https://wiki.zimbra.com/wiki/Security_Center","tags":["Release Notes","Vendor Advisory","web"]},{"url":"https://wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_Policy","tags":["Product","web"]},{"url":"https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.13#Security_Fixes","tags":["Release Notes","web"]},{"url":"https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.18#Security_Fixes","tags":["Release Notes","web"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-66376","tags":["government-resource","US Government Resource","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-66376","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-h7wg-85fj-3c6g"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66376.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2025-66376","description":"Zimbra Collaboration (ZCS) 10 before 10.0.18 and 10.1 before 10.1.13 allows Classic UI stored XSS via Cascading Style Sheets (CSS) @import directives in an HTML e-mail message.","status":"published","published":"2026-01-05T00:00:00Z","modified":"2026-03-19T03:55:17.926Z","cvss":[{"version":"3.1","score":7.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T14:32:53.157279Z"}],"euvd":[{"id":"EUVD-2026-0850","description":"Zimbra 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message.","status":"published","published":"2026-01-05T15:32:15Z","modified":"2026-03-18T18:31:10Z","cvss":[{"version":"3.1","score":7.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N","level":"high"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T15:06:41.700997Z"}],"kev":[{"id":"CVE-2025-66376","title":"Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability","description":"Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting vulnerability in the Classic UI where attackers could abuse Cascading Style Sheets (CSS) @import directives in email HTML.","cwes":["CWE-79"],"kev":{"date_added":"2026-03-18","due_date":"2026-04-01","required_action":"Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","known_ransomware_use":"Unknown"},"updated_at":"2026-11-02T17:00:15.999436Z"}],"nvd":[{"id":"CVE-2025-66376","description":"Zimbra Collaboration (ZCS) 10 before 10.0.18 and 10.1 before 10.1.13 allows Classic UI stored XSS via Cascading Style Sheets (CSS) @import directives in an HTML e-mail message.","status":"published","published":"2026-01-05T15:15:44.903Z","modified":"2026-10-07T10:10:00.213Z","cvss":[{"version":"3.1","score":7.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N","level":"high","assessor":"secondary"},{"version":"3.1","score":6.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T14:11:55.613137Z"}],"osv":[{"id":"CVE-2025-66376","description":"Zimbra Collaboration (ZCS) 10 before 10.0.18 and 10.1 before 10.1.13 allows Classic UI stored XSS via Cascading Style Sheets (CSS) @import directives in an HTML e-mail message.","status":"published","published":"2026-01-05T00:00:00Z","modified":"2026-11-09T02:45:59.375173515Z","cvss":[{"version":"3.1","score":7.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N","level":"high"}],"cwes":["CWE-79"],"updated_at":"2026-11-09T03:16:24.800471Z"}]}}