CVE-2026-43634 HIGH

CVE-2026-43634: HestiaCP 1.2.0-1.9.4 IP Spoofing via CF-Connecting-IP Header

Vendor Hestiacp
Product hestiacp
Weakness CWE-348
Published May 19, 2026
Last update May 19, 2026

CVSS base score

8.7/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

May 19, 2026 CVE published
May 19, 2026 Record updated