CVE-2026-66911 Stored Cross-Site Scripting in Zimbra
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-66911?
CVE-2026-66911 is a medium-severity vulnerability in Synacor Zimbra Collaboration, published on 29 Oct 2026.
Official description
Zimbra is vulnerable to stored cross-site scripting (XSS) via the Content-Location MIME header in email attachments. Due to lack of sanitization of the Content-Location header, an attacker can set it to a javascript: URI. An unauthenticated remote attacker can send a crafted email to a victim; when the victim opens the email in the Zimbra web interface and clicks the attachment name, the JavaScript payload executes in the victim's browser context. This issue was fixed in version 10.1.21
Weakness: CWE-79
Which versions are affected by CVE-2026-66911?
How do I fix CVE-2026-66911?
No fix has been published for CVE-2026-66911 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-66911 being exploited?
There is no known exploitation of CVE-2026-66911 in the wild and no public exploit code.
Sources
Also known as GHSA-4r7g-97vg-fv7w.