CVE-2026-33370 Cross-site scripting in n/a

Medium 6.1 Published 20 Mar 2026 Updated 23 Mar 2026

Attackers can execute arbitrary scripts in victim sessions via malicious files in Zimbra Briefcase, leading to data theft or account takeover.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2026-33370?

CVE-2026-33370 is a medium-severity cross-site scripting vulnerability in Synacor Zimbra Collaboration Suite, published on 20 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

An issue was discovered in Zimbra Collaboration (ZCS) 10.0 and 10.1. A stored cross-site scripting (XSS) vulnerability exists in the Zimbra Briefcase feature due to insufficient sanitization of specific uploaded file types. When a user opens a publicly shared Briefcase file containing malicious scripts, the embedded JavaScript executes in the context of the user's session. This allows an attacker to run arbitrary scripts, potentially leading to data exfiltration or other unauthorized actions on behalf of the victim user.

Weakness: CWE-79

Which versions are affected by CVE-2026-33370?

It affects 1 product.

Products include Synacor Zimbra Collaboration Suite.

How do I fix CVE-2026-33370?

No fix has been published for CVE-2026-33370 yet. Limit exposure of the affected software until one is available.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2026-33370 being exploited?

There is no known exploitation of CVE-2026-33370 in the wild and no public exploit code.

All Synacor Zimbra Collaboration Suite vulnerabilities

Sources

Also known as GHSA-cwch-jfrm-2v7r.