CVE-2025-48700 Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting

Exploited in the wild Medium 6.1 Published 23 Jun 2025 Updated 21 Apr 2026

Attackers can execute arbitrary JavaScript in Zimbra Classic UI via crafted emails, potentially stealing sensitive data or taking over accounts.

Exploited in the wild: Since 20 Apr 2026
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-2025-48700?

CVE-2025-48700 is a medium-severity cross-site scripting vulnerability in Synacor Zimbra Collaboration Suite, published on 23 Jun 2025. 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) 8.8.15 and 9.0 and 10.0 and 10.1. A Cross-Site Scripting (XSS) vulnerability in the Zimbra Classic UI allows attackers to execute arbitrary JavaScript within the user's session, potentially leading to unauthorized access to sensitive information. This issue arises from insufficient sanitization of HTML content, specifically involving crafted tag structures and attribute values that include an @import directive and other script injection vectors. The vulnerability is triggered when a user views a crafted e-mail message in the Classic UI, requiring no additional user interaction.

Weakness: CWE-79

Which versions are affected by CVE-2025-48700?

It affects 1 product.

Products include Synacor Zimbra Collaboration Suite.

How do I fix CVE-2025-48700?

No fix has been published for CVE-2025-48700 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 23 Apr 2026.

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-2025-48700 being exploited?

Yes. Attackers have exploited CVE-2025-48700 in the wild since at least 20 Apr 2026.

All Synacor Zimbra Collaboration Suite vulnerabilities

Sources

Also known as GHSA-wmq6-ffv7-gqwf.