Read the docs
TI-2026-79898 Aliases CVE-2026-50053GHSA-vffh-47xc-pr68

Zimbra Collaboration Suite RestFilter Attribute Override via URL Parameters

Priority LOW 39CWE-642Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
Required
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · None
Fix status
No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

Unauthenticated requests to /h/* can populate servlet attributes intended for trusted internal dispatch in Zimbra Collaboration Suite (ZCS). RestFilter copies URL parameters for the authentication token, target account, target item and dispatch state into request attributes that the Classic Web Client consumes. An attacker who combines this with CVE-2026-10632 on ZCS 10.1.16 can supply their own valid token and document identifiers and run JavaScript in another user's signed-in browser session. ZCS 10.1.17 blocks that XSS chain by changing the document renderer, but it keeps the request attribute override.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00289 21st percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ZimbraZimbra Collaboration Suiteup to 10.1.17—No fix listedCNA
  • Zimbra Collaboration Suite VendorZimbra Affected up to 10.1.17 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*up to 10.1.17VulnerableSynacor
  • cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:* Versions up to 10.1.17 Vulnerable ·Synacor

Remediation

No fixed version is listed for ZCS. Version 10.1.17 blocks the XSS chain by changing the document renderer, but the request attribute override remains, so upgrading to 10.1.17 does not remove the underlying exposure.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Timeline

  1. 2026-10-23 Threatist record created from CVE-2026-50053
  2. 2026-10-23 Alias added: GHSA-vffh-47xc-pr68
  3. 2026-10-24 Priority changed: MEDIUM → LOW
  4. 2026-10-28 CISA SSVC decision points changed
  5. 2026-11-02 CVSS score added · NVD

References

Advisory 1

Other 1

  • TI-2026-51660 OS command injection in Zimbra Collaboration KEVCVSS 3.1HIGH 8.9
  • TI-2025-40820 Cross-site scripting in Zimbra Collaboration KEVCVSS 3.1HIGH 7.2
  • TI-2024-18266 An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0. KEVCVSS 3.1MEDIUM 6.1
  • TI-2024-30553 An issue was discovered in Zimbra Collaboration (ZCS) 10.1.x before 10.1.1, 10.0.x before… CVSS 3.1HIGH 8.8
  • TI-2022-13998 Zimbra Collaboration Open Source 8.8.15 does not encrypt the initial-login randomly… CVSS 3.1CRITICAL 9.8
  • TI-2026-63080 Path traversal in Zimbra Collaboration Suite CVSS 3.1CRITICAL 9.8
See all 94 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences