CVE-2021-35209
9.8 · CRITICALOverview
CVE-2021-35209 is a critical-severity vulnerability affecting zimbra collaboration. It was published on July 2, 2021 and has a CVSS 3.1 base score of 9.8 (CRITICAL).
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical 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).
Remediation
Check the references section for vendor advisories and patches from zimbra. Update collaboration to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| zimbra | collaboration | >= 8.8, < 8.8.15 | Affected |
References
Frequently Asked Questions
What is CVE-2021-35209?
CVE-2021-35209 is a critical-severity vulnerability affecting zimbra collaboration. It was published on July 2, 2021 and has a CVSS 3.1 base score of 9.8 (CRITICAL).
How severe is CVE-2021-35209?
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-35209?
Check the references section for vendor advisories and patches from zimbra. Update collaboration to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-35209?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-35209 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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