CVE-2021-35209

CRITICAL

Zimbra Collaboration Suite 8.8-8.8.14 and 9.0.0-9.0.0.15 - Server-Side Request Forgery via X-Host Header

Title source: llm
STIX 2.1

Description

An issue was discovered in ProxyServlet.java in the /proxy servlet in Zimbra Collaboration Suite 8.8 before 8.8.15 Patch 23 and 9.x before 9.0.0 Patch 16. The value of the X-Host header overwrites the value of the Host header in proxied requests. The value of X-Host header is not checked against the whitelist of hosts Zimbra is allowed to proxy to (the zimbraProxyAllowedDomains setting).

References (5)

Core 5
Core References
Release Notes, Vendor Advisory x_refsource_misc
https://wiki.zimbra.com/wiki/Security_Center
Release Notes, Vendor Advisory x_refsource_misc
https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16
Release Notes, Vendor Advisory x_refsource_misc
https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23
Exploit, Third Party Advisory x_refsource_misc
https://blog.sonarsource.com/zimbra-webmail-compromise-via-email

Scores

CVSS v3 9.8
EPSS 0.0297
EPSS Percentile 85.5%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Details

CWE
CWE-918
Status published
Products (3)
zimbra/collaboration 8.8.15 (20 CPE variants)
zimbra/collaboration 9.0.0 (13 CPE variants)
zimbra/collaboration 8.8 - 8.8.15
Published Jul 02, 2021
Tracked Since Feb 18, 2026