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CVE-2026-50053 Details

Description

A request attribute override vulnerability in Zimbra Collaboration Suite (ZCS) allows unauthenticated requests to /h/* to populate servlet attributes intended for trusted internal dispatch. RestFilter copies URL parameters specifying an authentication token, target account, target item and dispatch state into the request attributes consumed by the Classic Web Client. Combined with CVE-2026-10632 on ZCS 10.1.16, this allows an attacker to supply their own valid token and document identifiers and execute JavaScript in another user's signed-in browser session. ZCS 10.1.17 blocks that XSS chain by changing the document renderer, but retains the request attribute override.

Metrics

CVSS 3.x Severity and Vector Strings:

NIST: [email protected]CVSS-B:5.4 MEDIUMVector:CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CNA: [email protected]CVSS-B:8.7 HIGHVector:CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories	[email protected]	Vendor Advisory
https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/	[email protected]	Not Applicable

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-642	External Control of Critical State Data	[email protected]

Affected Products

Product	Versions
synacor zimbra collaboration suite	<= 10.1.17
CPE cpe:2.3:a:synacor:zimbra_collaboration_suite:::::::: Remediation No remediation found in references.

Change History

3 change records found show changes

Date	Action	Recorded By
Nov 2, 2026	Initial Analysis	[email protected]
Oct 28, 2026	CVE Modified	CISA-ADP
Oct 23, 2026	New CVE Received	[email protected]