CVE-2021-35209

PoC —

CVSS 3.1

9.8 critical

EPSS

3%p87

Published

Jul 2, 2021 (Jul 2, 2021)

Modified

Jun 17, 2026

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).

Vendors: zimbra
Products: collaboration
Weakness: CWE-918
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

NVD CVE.org GitHub PoCs EPSS (3.0%)

In the news2 stories

Flaws in Zimbra could allow to takeover webmail server of an organization

Security AffairsJul 27, 20:35 UTC · Jul 27, 2021Vulnerability CVE-2021-35208 CVE-2021-35209

New Bug Could Let Attackers Hijack Zimbra Server by Sending Malicious Email

The Hacker NewsJul 27, 15:46 UTC · Jul 27, 2021Vulnerability CVE-2021-35208 CVE-2021-35209