{"cve":{"cve_id":"CVE-2025-66376","is_kev":true,"kev_date_added":"2026-03-18","kev_vendor_project":"Synacor","kev_product":"Zimbra Collaboration Suite (ZCS)","kev_vulnerability_name":"Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability","kev_short_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.","kev_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.","kev_due_date":"2026-04-01","kev_known_ransomware":false,"kev_notes":"https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories ; https://nvd.nist.gov/vuln/detail/CVE-2025-66376","kev_cwes":["CWE-79"],"epss_score":0.19304,"epss_percentile":0.97137,"epss_as_of":"2026-08-26","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.","published_at":"2026-01-05T00:00:00Z","last_modified_at":null,"cvss_v3_score":7.2,"cvss_v3_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N","cvss_v3_severity":"HIGH","cvss_v4_score":null,"cvss_v4_vector":null,"cvss_v4_severity":null,"ssvc_decision":null,"ssvc_exploitation":"active","ssvc_automatable":false,"ssvc_technical_impact":"partial","cwes":["CWE-79"],"nvd_references":["https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories","https://wiki.zimbra.com/wiki/Security_Center","https://wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_Policy","https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.13#Security_Fixes","https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.18#Security_Fixes"],"vuln_status":null,"trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-06-24T00:09:31.350578Z","updated_at":"2026-06-29T23:46:59.033383Z"},"effective_severity":"HIGH","badges":["kev"],"impact_analysis":[],"cvss_v3_decoded":{"version":"3.1","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"L","value_label":"Low"},{"metric":"PR","name":"Privileges Required","value":"N","value_label":"None"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"S","name":"Scope","value":"C","value_label":"Changed"},{"metric":"C","name":"Confidentiality","value":"L","value_label":"Low"},{"metric":"I","name":"Integrity","value":"L","value_label":"Low"},{"metric":"A","name":"Availability","value":"N","value_label":"None"}]},"cvss_v4_decoded":{"version":null,"metrics":[]},"affected":[{"vendor_slug":"zimbra","vendor_name":"Zimbra","product_slug":"collaboration","product_name":"Collaboration","version_start":"10.0","version_start_inclusive":true,"version_end":"10.0.18","version_end_inclusive":false,"cpe23_uri":"cve5:zimbra:collaboration:10.0:10.0.18"},{"vendor_slug":"zimbra","vendor_name":"Zimbra","product_slug":"collaboration","product_name":"Collaboration","version_start":"10.1","version_start_inclusive":true,"version_end":"10.1.13","version_end_inclusive":false,"cpe23_uri":"cve5:zimbra:collaboration:10.1:10.1.13"}],"exploit_refs":[],"news":[],"references":[{"url":"https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories","source_type":"VENDOR_ADVISORY","tags":["advisory"]},{"url":"https://wiki.zimbra.com/wiki/Security_Center","source_type":"MISC","tags":[]},{"url":"https://wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_Policy","source_type":"MISC","tags":[]},{"url":"https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.13#Security_Fixes","source_type":"MISC","tags":[]},{"url":"https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.18#Security_Fixes","source_type":"MISC","tags":[]}],"timeline":[{"type":"published","at":"2026-01-05T00:00:00Z","label":"CVE published","source":null},{"type":"cisa_reported","at":"2026-03-18T00:00:00Z","label":"Added to CISA KEV catalog","source":"kev"},{"type":"cvss_changed","at":"2026-06-28T17:49:06.072201Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:49:06.072201Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:49:06.072201Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"ssvc_changed","at":"2026-06-29T23:46:59.033383Z","label":"SSVC decision revised","source":"vulnrichment"},{"type":"ssvc_changed","at":"2026-06-29T23:46:59.033383Z","label":"SSVC decision revised","source":"vulnrichment"},{"type":"ssvc_changed","at":"2026-06-29T23:46:59.033383Z","label":"SSVC decision revised","source":"vulnrichment"}]}