CVE-2021-35209

high-risk
Published 2021-07-02

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).

Do I need to act?

~
2.5% chance of exploitation in next 30 days
EPSS score — moderate exploit probability
-
Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
9
CVSS 9.8/10 Critical
NETWORK / LOW complexity

Affected Products (20)

Affected Vendors

Zimbra

References (10)

Exploit https://blog.sonarsource.com/zimbra-webmail-compromise-via-email
Release Notes https://wiki.zimbra.com/wiki/Security_Center
Release Notes https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23
Release Notes https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16
Vendor Advisory https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
Exploit https://blog.sonarsource.com/zimbra-webmail-compromise-via-email
Release Notes https://wiki.zimbra.com/wiki/Security_Center
Release Notes https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23
Release Notes https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16
Vendor Advisory https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
61
/ 100
high-risk
Severity 32/34 · Critical
Exploitability 6/34 · Minimal
Exposure 23/34 · High