CVE-2026-43634Public exploitNetwork attack vector

Authentication bypass via trusted proxy header

Published May 19, 2026 · Updated May 19, 2026

IP spoofing in Hestia Control Panel 1.2.0 through 1.9.4 allows remote attackers to bypass IP-based controls via a crafted HTTP header. The login handler and get_real_user_ip() accept CF-Connecting-IP as the client address after syntax validation, without confirming that REMOTE_ADDR belongs to Cloudflare. Direct access to port 8083 lets an unauthenticated request rotate spoofed addresses to evade fail2ban, bypass per-user IP allowlists, and falsify authentication logs.

CVSS severity8.7
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

IP spoofing in Hestia Control Panel 1.2.0 through 1.9.4 allows remote attackers to bypass IP-based controls via a crafted HTTP header. The login handler and get_real_user_ip() accept CF-Connecting-IP as the client address after syntax validation, without confirming that REMOTE_ADDR belongs to Cloudflare. Direct access to port 8083 lets an unauthenticated request rotate spoofed addresses to evade fail2ban, bypass per-user IP allowlists, and falsify authentication logs.

The record

CVE
CVE-2026-43634
Published
May 19, 2026
Updated
May 19, 2026
Vendor
Hestia Control Panel
Product
Hestia Control Panel
Classifications
CWE-348, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 19, 2026CVE publishedPublication date reported by the CVE source.
  2. May 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.2.0 <=1.9.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hestia Control Panel · Hestia Control Panelversion=1.2.0 <=1.9.4

Published CVSS scores

8.7VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
7.5VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-348Use of Less Trusted Source
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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