{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-93633", "assignerOrgId": "9974b330-7714-4307-a722-5648477acda7", "state": "PUBLISHED", "assignerShortName": "rapid7", "dateReserved": "2026-09-18T12:22:34.911Z", "datePublished": "2026-10-23T13:25:21.365Z", "dateUpdated": "2026-10-23T13:25:21.365Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "9974b330-7714-4307-a722-5648477acda7", "shortName": "rapid7", "dateUpdated": "2026-10-23T13:25:21.365Z"}, "title": "Zimbra Collaboration Suite Briefcase CSS Sanitization Bypass via Non-ASCII Stylesheet Characters", "datePublic": "2026-10-23T12:54:00.000Z", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-79", "description": "CWE-79 Improper neutralization of input during web page generation ('cross-site scripting')", "type": "CWE"}]}], "affected": [{"vendor": "Zimbra", "product": "Zimbra Collaboration Suite", "versions": [{"status": "affected", "version": "0", "lessThanOrEqual": "10.1.20", "versionType": "semver"}], "defaultStatus": "unaffected"}], "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.", "supportingMedia": [{"type": "text/html", "base64": false, "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."}]}], "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"}}], "credits": [{"lang": "en", "value": "Jonah Burgess (CryptoCat), Senior Security Researcher, Rapid7", "type": "finder"}], "source": {"discovery": "UNKNOWN"}, "x_generator": {"engine": "Vulnogram 1.0.5"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Zimbra Collaboration Suite", "vendor": "Zimbra", "versions": [{"lessThanOrEqual": "10.1.20", "status": "affected", "version": "0", "versionType": "semver"}]}], "source": "cve@rapid7.com"}], "cveTags": [], "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."}], "id": "CVE-2026-93633", "lastModified": "2026-10-23T14:17:57.143", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 5.4, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "LOW", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 2.3, "impactScore": 2.7, "source": "cve@rapid7.com", "type": "Secondary"}]}, "published": "2026-10-23T14:17:57.143", "references": [{"source": "cve@rapid7.com", "url": "https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories"}, {"source": "cve@rapid7.com", "url": "https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/"}], "sourceIdentifier": "cve@rapid7.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-79"}], "source": "cve@rapid7.com", "type": "Secondary"}]}

{}

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