CVE-2026-93631

CVE-2026-93631 · Zimbra Collaboration Suite OAuth Extension Cross-Site Request Forgery Enables Account Linking

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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 7.1 · High

Published

2026-10-23T13:23:34.952Z

Updated

2026-10-23T13:23:34.952Z

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