CVE-2026-43633 CRITICAL

CVE-2026-43633: HestiaCP 1.9.0-1.9.4 Deserialization RCE via Web Terminal

Vendor Hestiacp
Product hestiacp
Weakness CWE-502 · Unsafe deserialization
Published May 19, 2026
Last update May 19, 2026

CVSS base score

9.5/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

What the vulnerability does

01Description

HestiaCP versions 1.9.0 through 1.9.4 contain a deserialization vulnerability in the web terminal component caused by a session format mismatch between PHP and Node.js that allows unauthenticated remote attackers to achieve root-level code execution. Attackers can inject crafted data into HTTP headers that are processed by the PHP session handler but incorrectly deserialized by the Node.js web terminal component as trusted session values, resulting in arbitrary command execution on systems with the web terminal feature enabled.

Key dates

02Disclosure timeline

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