Is CVE-2026-93630 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-93630 being exploited in the wild.

How severe is CVE-2026-93630?

Medium severity, with a CVSS score of 4.3, published 23 October 2026.

Which products and versions are affected?

Zimbra Collaboration Suite 10.1.16, 10.1.21.

Is there a fix for CVE-2026-93630?

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-2026-93630 attacked?

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

Am I affected by CVE-2026-93630?

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-2026-93630: Zimbra Collaboration Suite hostname canonicalization in email sanitizer

CVE-2026-93630 · Severity: medium · CVSS 4.3 · Published 2026-10-23

Zimbra Collaboration Suite is an enterprise email and collaboration platform that stores sensitive communications and user identities. A vulnerability in its email HTML sanitizer allows an attacker to craft a malicious email that, when opened and a form is submitted by the recipient, sends authenticated requests to the Zimbra server using the victim's login session. This could enable account takeover, data theft, or unauthorized actions if the target endpoint lacks additional CSRF protections.

Technologies: Zimbra Collaboration Suite. Vendors: Zimbra.

Quick answers

Is CVE-2026-93630 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-93630 being exploited in the wild.
How severe is CVE-2026-93630?: Medium severity, with a CVSS score of 4.3, published 23 October 2026.
Which products and versions are affected?: Zimbra Collaboration Suite 10.1.16, 10.1.21.
Is there a fix for CVE-2026-93630?: 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-2026-93630 attacked?: It is attacked over the network, in a web application.
Am I affected by CVE-2026-93630?: 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 hostname canonicalization flaw in DefangFilter and OWASP ActionAttributePolicy allows percent-encoded hostnames to bypass form-action validation while the browser canonicalizes them to the legitimate Zimbra origin during form submission. An unauthenticated attacker sends a crafted email with a malicious form targeting a percent-encoded Zimbra hostname; when the recipient opens it in Classic and submits the form, the browser resolves it to the real host and sends the request with the recipient's authentication cookie. The vulnerability does not bypass CSRF tokens, so exploitation requires a state-changing endpoint without that protection.

Affected products

Zimbra Collaboration Suite 10.1.16, 10.1.21

Timeline

2026-10-23: disclosed

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.