SSRF in Zimbra Collaboration
CVE-2021-35209
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).
Vulnerability class: SSRF (Server-Side Request Forgery)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.030 (86.8th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 87th percentile — 86.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.030 · newest: 0.030 · change: 0.000
Affected products
- Zimbra Collaboration — versions 8.8.15, 9.0.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- wiki.zimbra.com/wiki/Zimbra_Security_Advisories (Vendor Advisory)
- wiki.zimbra.com/wiki/Security_Center (Release Notes, Vendor Advisory)
- wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16 (Release Notes, Vendor Advisory)
- wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23 (Release Notes, Vendor Advisory)
- blog.sonarsource.com/zimbra-webmail-compromise-via-email (Exploit, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-35209?
- CVE-2021-35209 is a critical-severity vulnerability in Zimbra Collaboration, classified under Server-Side Request Forgery (SSRF). CVSS score: 9.8/10. Published 2021-07-02.
- How severe is CVE-2021-35209?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2021-35209 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.