{"id":"CVE-2026-93633","state":"PUBLISHED","title":"Zimbra Collaboration Suite Briefcase CSS Sanitization Bypass via Non-ASCII Stylesheet Characters","description":"A CSS sanitization vulnerability in Zimbra Collaboration Suite (ZCS) allows an authenticated user with Briefcase access to publish a document that displays attacker-controlled content under the Zimbra origin. When processing a stylesheet containing non-ASCII characters, DefangFilter appends the final ASCII segment without sanitizing it. HTML stored as application/x-zimbra-doc can therefore retain CSS URL references that the normal sanitizer removes. An attacker can share a crafted document that loads external resources and displays a credential-collection form using Zimbra's own visual assets. Exploitation requires the victim to open the document in a browser that renders the content type inline; credential theft additionally requires form submission. ZCS 10.1.16 and 10.1.20 are affected.","publishedAt":"2026-10-23T13:25:21.365Z","updatedAt":"2026-10-28T19:51:07.972Z","severity":{"score":5.4,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","source":"rapid7"},"assigner":"rapid7","products":["Zimbra Zimbra Collaboration Suite"],"affected":[{"vendor":"Zimbra","product":"Zimbra Collaboration Suite","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"10.1.20","versionType":"semver"}]}],"references":["https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories","https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/"],"weaknesses":["CWE-79"],"ingestedAt":"2026-10-29T20:13:34.582Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/93xxx/CVE-2026-93633.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-93633","state":"PUBLISHED","datePublished":"2026-10-23T13:25:21.365Z","dateUpdated":"2026-10-28T19:51:07.972Z","assignerShortName":"rapid7","assignerOrgId":"9974b330-7714-4307-a722-5648477acda7","dateReserved":"2026-09-18T12:22:34.911Z"},"containers":{"cna":{"title":"Zimbra Collaboration Suite Briefcase CSS Sanitization Bypass via Non-ASCII Stylesheet Characters","descriptions":[{"lang":"en","value":"A CSS sanitization vulnerability in Zimbra Collaboration Suite (ZCS) allows an authenticated user with Briefcase access to publish a document that displays attacker-controlled content under the Zimbra origin. When processing a stylesheet containing non-ASCII characters, DefangFilter appends the final ASCII segment without sanitizing it. HTML stored as application/x-zimbra-doc can therefore retain CSS URL references that the normal sanitizer removes. An attacker can share a crafted document that loads external resources and displays a credential-collection form using Zimbra's own visual assets. Exploitation requires the victim to open the document in a browser that renders the content type inline; credential theft additionally requires form submission. ZCS 10.1.16 and 10.1.20 are affected."}],"affected":[{"vendor":"Zimbra","product":"Zimbra Collaboration Suite","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"10.1.20","versionType":"semver"}]}],"references":[{"url":"https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories","tags":["vendor-advisory"]},{"url":"https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/","tags":["related"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV3_1":{"version":"3.1","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"REQUIRED","scope":"CHANGED","confidentialityImpact":"LOW","integrityImpact":"LOW","availabilityImpact":"NONE","baseSeverity":"MEDIUM","baseScore":5.4,"vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-79","lang":"en","description":"CWE-79 Improper neutralization of input during web page generation ('cross-site scripting')","type":"CWE"}]}],"providerMetadata":{"shortName":"rapid7","orgId":"9974b330-7714-4307-a722-5648477acda7","dateUpdated":"2026-10-23T13:25:21.365Z"},"datePublic":"2026-10-23T12:54:00.000Z","credits":[{"lang":"en","value":"Jonah Burgess (CryptoCat), Senior Security Researcher, Rapid7","type":"finder"}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"Vulnogram 1.0.5"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-28T17:48:57.736632Z","id":"CVE-2026-93633","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-28T19:51:07.972Z"}}]}}}