Is CVE-2026-50053 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-50053 being exploited in the wild.

How severe is CVE-2026-50053?

High severity, with a CVSS score of 8.7, published 23 October 2026.

Which products and versions are affected?

Zimbra Collaboration Suite 10.1.16 and earlier; 10.1.17 partially affected.

Is there a fix for CVE-2026-50053?

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-2026-50053 attacked?

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

Am I affected by CVE-2026-50053?

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-2026-50053: Zimbra Collaboration Suite request attribute override

CVE-2026-50053 · Severity: high · CVSS 8.7 · Published 2026-10-23

Zimbra Collaboration Suite is an enterprise email and collaboration platform used for mail, calendars, contacts, and file sharing. A vulnerability in how the web server processes requests allows unauthenticated attackers to inject malicious authentication tokens and account identifiers, which can lead to unauthorized access to other users' mailboxes and data when combined with other flaws. An attacker can potentially read private emails, attachments, calendars, and contacts belonging to other users.

Technologies: Zimbra Collaboration Suite. Vendors: Zimbra.

Quick answers

Is CVE-2026-50053 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-50053 being exploited in the wild.
How severe is CVE-2026-50053?: High severity, with a CVSS score of 8.7, published 23 October 2026.
Which products and versions are affected?: Zimbra Collaboration Suite 10.1.16 and earlier; 10.1.17 partially affected.
Is there a fix for CVE-2026-50053?: 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-2026-50053 attacked?: It is attacked over the network, in a web application.
Am I affected by CVE-2026-50053?: 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

The RestFilter in Zimbra's Classic Web Client copies URL parameters specifying authentication tokens, target accounts, target items, and dispatch state into servlet request attributes without validation, allowing unauthenticated requests to /h/* paths to populate internal dispatch state. When combined with CVE-2026-10632 on ZCS 10.1.16, this enables stored XSS execution in another user's browser session; ZCS 10.1.17 blocks the XSS chain via document renderer changes but the underlying request attribute override persists. The vulnerability requires network access and can be exploited by an unauthenticated attacker supplying a valid token and document identifiers.

Affected products

Zimbra Collaboration Suite 10.1.16 and earlier; 10.1.17 partially affected

Timeline

2026-10-23: disclosed

References

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