{"id":"CVE-2026-43634","summary":"HestiaCP 1.2.0-1.9.4 IP Spoofing via CF-Connecting-IP Header","details":"HestiaCP versions 1.2.0 through 1.9.4 contain an IP spoofing vulnerability that allows unauthenticated remote attackers to bypass authentication security controls by supplying an arbitrary IP address in the CF-Connecting-IP HTTP header without verifying the request originated from Cloudflare's network. Attackers can exploit this to circumvent fail2ban brute-force protection, bypass per-user IP allowlists, and poison authentication audit logs by spoofing trusted IP addresses on each request.","modified":"2026-07-08T08:13:27.122889521Z","published":"2026-05-19T13:33:08.825Z","database_specific":{"cna_assigner":"VulnCheck","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43634.json","cwe_ids":["CWE-348"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43634.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-43634"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/hestiacp-ip-spoofing-via-cf-connecting-ip-header"},{"type":"REPORT","url":"https://github.com/hestiacp/hestiacp/issues/5229"},{"type":"REPORT","url":"https://github.com/hestiacp/hestiacp/pull/5273"},{"type":"FIX","url":"https://github.com/hestiacp/hestiacp/commit/f381e294500f671cf12716c638afd0bfde901f88"},{"type":"PACKAGE","url":"https://github.com/hestiacp/hestiacp"},{"type":"EVIDENCE","url":"https://mercuryiss.com.au/hestiacp-unauthenticated-rce-ip-spoofing-cve-2026-43633-cve-2026-43634"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/hestiacp/hestiacp","events":[{"introduced":"8e399f2ab2227dd31d38cebebb738b163534c8d5"},{"fixed":"aae8b2b40bf78fe571d12d49f3a2e5b5ada7d38e"},{"fixed":"f381e294500f671cf12716c638afd0bfde901f88"}],"database_specific":{"source":["DESCRIPTION","REFERENCES"],"extracted_events":[{"introduced":"1.2.0"},{"fixed":"1.9.4"}]}}],"versions":["1.9.3","1.9.2","1.9.1","1.9.0","1.8.0","1.7.0","1.5.0","1.4.14","1.4.13","1.4.12","1.4.11","1.4.10","1.4.9","1.4.8","1.4.7","1.4.6","1.4.5","1.4.4","1.4.3","1.4.2","1.4.1","1.4.0","1.2.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-43634.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"}]}