CVE Catalog

CVE-2026-93631

HighCVSS 7.1
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.18%

7th percentile - higher than 7% of all known CVEs

Summary

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 selects the destination mailbox from the browser's current authentication cookie. An attacker can induce a signed-in victim to load a callback with a fresh code for the attacker's account, creating a persistent data source that imports attacker-controlled contacts or events; with bidirectional CalDAV synchronization, calendar appointments are also disclosed.

Risk Assessment

An attacker can persistently link their account to the victim's mailbox, import malicious data, and exfiltrate calendar information, impacting confidentiality and integrity.

Recommendation

Update ZCS to the patched version. Review configured OAuth links and remove unknown linked accounts.

Related vulnerabilities

Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS