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CVE PROGRAM SOURCE RECORD5.4 Medium

CVE-2026-93633

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Zimbra Zimbra Collaboration Suite

Default version status: unaffected

  • 0 to ≤ 10.1.20affected

References