CVE-2026-43633

Critical

Description

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.

SeverityCritical

CVSS10.0

Exploit probability—

ProductHestiacp

PublishedMay 19, 2026

First seenMay 19, 2026

Weakness typeCWE-502Deserialization of untrusted data

How to fix

Patches

github.com/hestiacp/hestiacp/commit/854d71b3c1737b0a0d0cc55c926008ffe1f6719b

Affected products

Product	Affected versions	Fixed in
hestiacp hestiacp	1.9.0 ≤ v ≤ 1.9.4	—

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