Vulnerability Description
A cross-site request forgery vulnerability in the OAuth extension of Zimbra Collaboration Suite (ZCS) Network Edition allows an attacker to link an attacker-controlled external account to a victim's mailbox. The OAuth callback does not bind its state value or authorization code to the initiating Zimbra session and instead selects the destination mailbox from the browser's current authentication cookie. On a deployment with the provider configured, an attacker can induce a signed-in victim to load a callback containing a fresh code for the attacker's provider account. This creates a persistent data source that imports attacker-controlled contacts or events. With bidirectional CalDAV synchronization, appointments subsequently created or edited in the linked calendar are also disclosed to the attacker. ZCS 10.1.16 and 10.1.20 are affected.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Synacor | Zimbra Collaboration Suite | <= 10.1.20 |
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-2026-93631?
CVE-2026-93631 is a vulnerability with a CVSS score of 7.1 (HIGH). A cross-site request forgery vulnerability in the OAuth extension of Zimbra Collaboration Suite (ZCS) Network Edition allows an attacker to link an attacker-controlled external account to a victim's m...
How severe is CVE-2026-93631?
CVE-2026-93631 has been rated HIGH with a CVSS base score of 7.1/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-93631?
Check the references section above for vendor advisories and patch information. Affected products include: Synacor Zimbra Collaboration Suite.