CVE-2026-43634 HestiaCP 1.2.0-1.9.4 IP Spoofing via CF-Connecting-IP Header
Unauthenticated attackers can bypass authentication controls and fail2ban protections by spoofing IP addresses via the CF-Connecting-IP header.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-43634?
CVE-2026-43634 is a high-severity authentication bypass vulnerability in hestiacp, published on 19 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-348
Which versions are affected by CVE-2026-43634?
How do I fix CVE-2026-43634?
No fix has been published for CVE-2026-43634 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-43634 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-43634 exists.
Sources
Also known as GHSA-72fg-f46j-5gvp.