CVE-2026-43634

Description

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.

References

• https://github.com/hestiacp/hestiacp/commit/f381e294500f671cf12716c638afd0bfde901f88
• https://github.com/hestiacp/hestiacp/issues/5229
• https://github.com/hestiacp/hestiacp/pull/5273
• https://mercuryiss.com.au/hestiacp-unauthenticated-rce-ip-spoofing-cve-2026-43633-cve-2026-43634
• https://www.vulncheck.com/advisories/hestiacp-ip-spoofing-via-cf-connecting-ip-header