{"id":"CVE-2021-35209","details":"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).","modified":"2026-04-10T04:35:02.395607Z","published":"2021-07-02T19:15:08.460Z","references":[{"type":"ADVISORY","url":"https://wiki.zimbra.com/wiki/Security_Center"},{"type":"ADVISORY","url":"https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23"},{"type":"ADVISORY","url":"https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16"},{"type":"ADVISORY","url":"https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories"},{"type":"EVIDENCE","url":"https://blog.sonarsource.com/zimbra-webmail-compromise-via-email"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/zimbra/zm-build","events":[{"introduced":"0"},{"fixed":"ac6081fa002b1511e926aba37740d2b6c20f3f43"},{"introduced":"0"},{"last_affected":"ac6081fa002b1511e926aba37740d2b6c20f3f43"},{"introduced":"0"},{"last_affected":"29eea219faf34718f0ef1cda7c3f02c89910c96c"},{"introduced":"0"},{"last_affected":"29eea219faf34718f0ef1cda7c3f02c89910c96c"},{"introduced":"0"},{"last_affected":"905970576d6fe337150f09c0ad7a0f53aa1a8f42"},{"introduced":"0"},{"last_affected":"0e40da921adb967639011de45841cef4c4601413"},{"introduced":"0"},{"last_affected":"b6cd8f69d2761c014d4a3807f0bdee0011386444"},{"introduced":"0"},{"last_affected":"5561a39cba0898c3bb5e188284d98f498d7a3c9a"},{"introduced":"0"},{"last_affected":"03d99a16095b73a73770fbb6131d10234cfc13fd"},{"introduced":"0"},{"last_affected":"bcb978ccc354d99d843725886083e321759b6765"}],"database_specific":{"versions":[{"introduced":"8.8"},{"fixed":"8.8.15"},{"introduced":"0"},{"last_affected":"8.8.15-NA"},{"introduced":"0"},{"last_affected":"8.8.15-p1"},{"introduced":"0"},{"last_affected":"8.8.15-p11"},{"introduced":"0"},{"last_affected":"8.8.15-p3"},{"introduced":"0"},{"last_affected":"8.8.15-p5"},{"introduced":"0"},{"last_affected":"9.0.0-NA"},{"introduced":"0"},{"last_affected":"9.0.0-p1"},{"introduced":"0"},{"last_affected":"9.0.0-p4"},{"introduced":"0"},{"last_affected":"9.0.0-p7"}]}}],"versions":["8.7.10","8.7.11","8.7.6","8.7.7","8.7.9","8.8.0.beta1","8.8.10","8.8.12","8.8.15","8.8.15.p11","8.8.15.p3","8.8.15.p5","8.8.2","8.8.3","8.8.4","8.8.6","8.8.7","8.8.8","8.8.9","8.8.9.p1","8.8.9.p3","9.0.0","9.0.0.p19","9.0.0.p4","9.0.0.p7","9.0.0.p7.1"],"database_specific":{"unresolved_ranges":[{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p10"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p12"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p13"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p14"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p15"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p16"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p17"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p18"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p19"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p2"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p4"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p6"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p7"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p8"}]},{"events":[{"introduced":"0"},{"last_affected":"8.8.15-p9"}]},{"events":[{"introduced":"0"},{"last_affected":"9.0.0-p10"}]},{"events":[{"introduced":"0"},{"last_affected":"9.0.0-p11"}]},{"events":[{"introduced":"0"},{"last_affected":"9.0.0-p12"}]},{"events":[{"introduced":"0"},{"last_affected":"9.0.0-p2"}]},{"events":[{"introduced":"0"},{"last_affected":"9.0.0-p3"}]},{"events":[{"introduced":"0"},{"last_affected":"9.0.0-p5"}]},{"events":[{"introduced":"0"},{"last_affected":"9.0.0-p6"}]},{"events":[{"introduced":"0"},{"last_affected":"9.0.0-p8"}]},{"events":[{"introduced":"0"},{"last_affected":"9.0.0-p9"}]}],"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-35209.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}