CVE-2026-73572 Cross-site scripting in Collaboration

Medium 6.1 Published 13 Aug 2026 Updated 13 Aug 2026

Stored XSS in Zimbra Classic Web Client allows attackers to execute JavaScript via malicious attachments, leading to data exfiltration 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-2026-73572?

CVE-2026-73572 is a medium-severity cross-site scripting vulnerability in Synacor Zimbra Collaboration Suite, published on 13 Aug 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

In Zimbra Collaboration (ZCS) before 10.1.17, a stored cross-site scripting (XSS) vulnerability exists in the Zimbra Classic Web Client due to insufficient sanitization of specific attachment content during inline preview. An attacker can send a crafted email containing a malicious attachment that, when previewed by a user, executes arbitrary JavaScript within the victim's browser session. Successful exploitation may allow an attacker to perform unauthorized actions on behalf of the victim user, potentially leading to data exfiltration or unauthorized access to sensitive information.

Weakness: CWE-79

Which versions are affected by CVE-2026-73572?

It affects 1 product.

Products include Synacor Zimbra Collaboration Suite.

How do I fix CVE-2026-73572?

No fix has been published for CVE-2026-73572 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-2026-73572 being exploited?

There is no known exploitation of CVE-2026-73572 in the wild and no public exploit code.

All Synacor Zimbra Collaboration Suite vulnerabilities

Sources

Also known as GHSA-4644-7rc8-9cw4.