Is CVE-2026-93633 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-93633 being exploited in the wild.

How severe is CVE-2026-93633?

Medium severity, with a CVSS score of 5.4, published 23 October 2026.

Which products and versions are affected?

Zimbra Collaboration Suite 10.1.16, 10.1.20.

Is there a fix for CVE-2026-93633?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-93633 attacked?

It is attacked over the network, in a web application.

Am I affected by CVE-2026-93633?

Check whether you run Zimbra Collaboration Suite at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-93633: Zimbra Collaboration Suite CSS sanitization bypass

CVE-2026-93633 · Severity: medium · CVSS 5.4 · Published 2026-10-23

Zimbra Collaboration Suite is an enterprise email and collaboration platform. An authenticated user can craft a malicious document in Briefcase that loads external resources and displays credential-stealing forms that appear to come from Zimbra itself, potentially capturing user login credentials. Exploitation requires the victim to open the document in a browser and, to steal credentials, to submit a form.

Technologies: Zimbra Collaboration Suite. Vendors: Zimbra.

Quick answers

Is CVE-2026-93633 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-93633 being exploited in the wild.
How severe is CVE-2026-93633?: Medium severity, with a CVSS score of 5.4, published 23 October 2026.
Which products and versions are affected?: Zimbra Collaboration Suite 10.1.16, 10.1.20.
Is there a fix for CVE-2026-93633?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-93633 attacked?: It is attacked over the network, in a web application.
Am I affected by CVE-2026-93633?: Check whether you run Zimbra Collaboration Suite at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A CSS sanitization vulnerability in the DefangFilter allows non-ASCII characters in stylesheets to bypass sanitization, leaving CSS URL references intact in documents stored as application/x-zimbra-doc. An authenticated attacker with Briefcase access can exploit this to craft documents with external resource references that would normally be removed by the sanitizer. The attack requires the victim to open the document in a browser that renders the content type inline and to interact with the malicious form.

Affected products

Zimbra Collaboration Suite 10.1.16, 10.1.20

Timeline

2026-10-23: disclosed

References

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