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Back to active CVEs
Medium · CVSS 5.4CVE-2026-93633

Zimbra Collaboration Suite Briefcase CSS Sanitization Bypass via Non-ASCII Stylesheet CharactersCVE-2026-93633

Answer in brief

CVE-2026-93633 records a Medium severity (CVSS 5.4) vulnerability in Zimbra Collaboration Suite Briefcase CSS Sanitization Bypass via Non-ASCII Stylesheet Characters. The current sources do not mark it as known exploited. The current feed maps Zimbra/Zimbra Collaboration Suite (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 23, 2026Updated Oct 23, 2026Source checked Oct 23, 2026First seen by HOL Oct 23, 2026Material review Oct 23, 2026
Upstream Advisory

Key facts

Risk
Medium · CVSS 5.4
Exploitation
Not marked as known exploited
Affected software
1 mapped package or product
Fix availability
Not reported

Why this deserves its current priority

CVSS is 5.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Zimbra/Zimbra Collaboration Suite (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
PackageAffected rangeFixed version
Zimbra/Zimbra Collaboration Suitegeneric>=0 <=10.1.20Not reported

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for Zimbra/Zimbra Collaboration Suite.
  2. 2Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

  1. Published upstream

    Oct 23, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Oct 23, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Oct 23, 2026

Sources and claim methodology

  • Source referencewiki.zimbra.com
  • Source referencerapid7.com
Upstream source 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.

Quoted source text, attributed separately from HOL analysis.

Related CVEs

  • Zimbra Collaboration Suite Data Source Test SMTP Command Injection via Unsanitized Email AddressSame zimbra/zimbra collaboration suite package
  • Zimbra Collaboration Suite Shared-File Mailbox Quota Accounting Error Enables Quota ExhaustionSame zimbra/zimbra collaboration suite package
  • Zimbra Collaboration Suite Local Privilege Escalation via zmmailboxdmgr JVM Argument InjectionSame zimbra/zimbra collaboration suite package
  • Zimbra Collaboration Suite Local Privilege Escalation via Unrestricted Postfix Sudo PermissionsSame zimbra/zimbra collaboration suite package
  • Zimbra Collaboration Suite Email HTML Sanitizer Bypass via Hostname CanonicalizationSame zimbra/zimbra collaboration suite package
  • Zimbra Collaboration Suite OAuth Extension Cross-Site Request Forgery Enables Account LinkingSame zimbra/zimbra collaboration suite package

Record context

Vulnerability class
XSS
EPSS
Not reported
CWE IDs
CWE-79
Source
CVE List V5
Source checked
Oct 23, 2026
References
2 linked sources
Open source record