CVE-2021-35209
The value of X-Host header is not checked against the whitelist of hosts Zimbra is allowed to proxy to (the zimbraProxyAllowedDomains setting).
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (3.00%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 3.00% probability · 87th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-918
- Affected
- zimbra/collaboration
- Source
- cve@mitre.org
References
- https://blog.sonarsource.com/zimbra-webmail-compromise-via-emailExploit, Third Party Advisory
- https://wiki.zimbra.com/wiki/Security_CenterRelease Notes, Vendor Advisory
- https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23Release Notes, Vendor Advisory
- https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16Release Notes, Vendor Advisory
- https://wiki.zimbra.com/wiki/Zimbra_Security_AdvisoriesVendor Advisory
- https://blog.sonarsource.com/zimbra-webmail-compromise-via-emailExploit, Third Party Advisory
- https://wiki.zimbra.com/wiki/Security_CenterRelease Notes, Vendor Advisory
- https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23Release Notes, Vendor Advisory
- https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16Release Notes, Vendor Advisory
- https://wiki.zimbra.com/wiki/Zimbra_Security_AdvisoriesVendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.