CVE-2021-35209 — CRITICAL (9.8)

Q: How severe is CVE-2021-35209?

CVE-2021-35209 has been rated CRITICAL with a CVSS base score of 9.8/10. This is considered a critical vulnerability requiring immediate attention.

Q: Is there a patch for CVE-2021-35209?

Check the references section above for vendor advisories and patch information. Affected products include: Zimbra Collaboration.

Vulnerability 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).

CVSS Score

9.8

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

HIGH

Integrity

HIGH

Availability

HIGH

Affected Products

Vendor	Product	Versions
Zimbra	Collaboration	>= 8.8, < 8.8.15

Related Weaknesses (CWE)

CWE-918

References

https://blog.sonarsource.com/zimbra-webmail-compromise-via-emailExploitThird Party Advisory
https://wiki.zimbra.com/wiki/Security_CenterRelease NotesVendor Advisory
https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23Release NotesVendor Advisory
https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16Release NotesVendor Advisory
https://wiki.zimbra.com/wiki/Zimbra_Security_AdvisoriesVendor Advisory
https://blog.sonarsource.com/zimbra-webmail-compromise-via-emailExploitThird Party Advisory
https://wiki.zimbra.com/wiki/Security_CenterRelease NotesVendor Advisory
https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23Release NotesVendor Advisory
https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16Release NotesVendor Advisory
https://wiki.zimbra.com/wiki/Zimbra_Security_AdvisoriesVendor Advisory

FAQ

What is CVE-2021-35209?

CVE-2021-35209 is a vulnerability with a CVSS score of 9.8 (CRITICAL). 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...

How severe is CVE-2021-35209?

CVE-2021-35209 has been rated CRITICAL with a CVSS base score of 9.8/10. This is considered a critical vulnerability requiring immediate attention.

Is there a patch for CVE-2021-35209?

Check the references section above for vendor advisories and patch information. Affected products include: Zimbra Collaboration.