CVE-2024-27443 Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS)
Attackers can execute arbitrary JavaScript in victim sessions via crafted calendar headers in Zimbra webmail, potentially leading to account takeover.
- Exploited in the wild
- Since 19 May 2025
- 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-2024-27443?
CVE-2024-27443 is a medium-severity cross-site scripting vulnerability in n/a, published on 12 Aug 2024. 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) 9.0 and 10.0. A Cross-Site Scripting (XSS) vulnerability exists in the CalendarInvite feature of the Zimbra webmail classic user interface, because of improper input validation in the handling of the calendar header. An attacker can exploit this via an email message containing a crafted calendar header with an embedded XSS payload. When a victim views this message in the Zimbra webmail classic interface, the payload is executed in the context of the victim's session, potentially leading to execution of arbitrary JavaScript code.
Weakness: CWE-79
Which versions are affected by CVE-2024-27443?
It affects 1 product.
Products include Zimbra Collaboration.
How do I fix CVE-2024-27443?
No fix has been published for CVE-2024-27443 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 9 Jun 2025.
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-2024-27443 being exploited?
Yes. Attackers have exploited CVE-2024-27443 in the wild since at least 19 May 2025.
Public exploit code: 1 Nuclei template.
Other vulnerabilities in n/a
Sources
Also known as GHSA-qrvg-mg33-q843.