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Vulnerability record · CVE-2026-43633 · published 19 May 2026

CVE-2026-43633: Deserialization of untrusted data vulnerability

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.

9.5 CVSS 4.0 Critical EPSS 1.5% · top 27.0% CWE-502 · Deserialization of untrusted data Deferred
9.5CVSS 4.0 base score
1.5%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
5References
14 Jul 2026Last modified by NVD

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.

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/hestiacp/hestiacp/commit/854d71b3c1737b0a0d0cc55c926008ffe1f6719b
https://github.com/hestiacp/hestiacp/issues/5229
https://github.com/hestiacp/hestiacp/pull/5244
https://mercuryiss.com.au/hestiacp-unauthenticated-rce-ip-spoofing-cve-2026-43633-cve-2026-43634
https://www.vulncheck.com/advisories/hestiacp-deserialization-rce-via-web-terminal

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Source: NIST National Vulnerability Database (record CVE-2026-43633), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.