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.
Published: 2026-10-23
Score: 7.1 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Wed, 28 Oct 2026 21:45:00 +0000

Type Values Removed Values Added
First Time appeared Synacor
Synacor zimbra Collaboration Suite
CPEs cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*
Vendors & Products Synacor
Synacor zimbra Collaboration Suite

Wed, 28 Oct 2026 20:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 23 Oct 2026 23:45:00 +0000

Type Values Removed Values Added
First Time appeared Zimbra
Zimbra zimbra Collaboration Suite
Vendors & Products Zimbra
Zimbra zimbra Collaboration Suite

Fri, 23 Oct 2026 13:30:00 +0000

Type Values Removed Values Added
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.
Title Zimbra Collaboration Suite OAuth Extension Cross-Site Request Forgery Enables Account Linking
Weaknesses CWE-352
References
Metrics cvssV3_1

{'score': 7.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N'}


Subscriptions

Synacor Zimbra Collaboration Suite
Zimbra Zimbra Collaboration Suite
cve-icon MITRE

Status: PUBLISHED

Assigner: rapid7

Published:

Updated: 2026-10-28T19:51:18.814Z

Reserved: 2026-09-18T12:22:34.911Z

Link: CVE-2026-93631

cve-icon Vulnrichment

Updated: 2026-10-28T17:48:55.827Z

cve-icon NVD

Status : Analyzed

Published: 2026-10-23T14:17:57.023

Modified: 2026-10-28T21:27:12.197

Link: CVE-2026-93631

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-23T23:30:17Z

Weaknesses