Vulnerability Description
A reflected cross-site scripting vulnerability in the login page of Zimbra Collaboration Suite (ZCS) allows an unauthenticated attacker to execute JavaScript through the zrememberme parameter. A crafted relogin URL selects a two-factor error display that inserts the parameter into a hidden input attribute without HTML encoding. A victim who opens the URL receives attacker-controlled script and page content under the legitimate Zimbra origin, allowing credential capture through a replacement login form. The relogin path logs out an existing session before rendering the payload, so the demonstrated attack does not inherit that session's mailbox access. ZCS 10.1.16 and 10.1.17 are affected.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Synacor | Zimbra Collaboration Suite | <= 10.1.17 |
Related Weaknesses (CWE)
References
- https://wiki.zimbra.com/wiki/Zimbra_Security_AdvisoriesVendor Advisory
- https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/ExploitThird Party Advisory
FAQ
What is CVE-2026-93638?
CVE-2026-93638 is a vulnerability with a CVSS score of 6.1 (MEDIUM). A reflected cross-site scripting vulnerability in the login page of Zimbra Collaboration Suite (ZCS) allows an unauthenticated attacker to execute JavaScript through the zrememberme parameter. A craft...
How severe is CVE-2026-93638?
CVE-2026-93638 has been rated MEDIUM with a CVSS base score of 6.1/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-93638?
Check the references section above for vendor advisories and patch information. Affected products include: Synacor Zimbra Collaboration Suite.