CVE-2021-35209 Server-side request forgery in n/a

Critical 9.8 Published 2 Jul 2021 Updated 4 Aug 2024

Attackers can bypass proxy restrictions in Zimbra Collaboration Suite by manipulating the X-Host header, potentially accessing unauthorized internal resources.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2021-35209?

CVE-2021-35209 is a critical server-side request forgery vulnerability in n/a, published on 2 Jul 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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).

Weakness: CWE-918

Which versions are affected by CVE-2021-35209?

It affects 1 product.

Products include Zimbra Collaboration.

How do I fix CVE-2021-35209?

No fix has been published for CVE-2021-35209 yet. Limit exposure of the affected software until one is available.

Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.

Is CVE-2021-35209 being exploited?

There is no known exploitation of CVE-2021-35209 in the wild and no public exploit code.

Sources

Also known as GHSA-wv5j-j74p-fv28.