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HestiaCP CVE-2026-43633

| EUVD-2026-30933 CRITICAL
Deserialization of Untrusted Data (CWE-502)
2026-05-19 VulnCheck GHSA-p57r-8pg4-2892
9.5
CVSS 4.0
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CVSS VectorNVD

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:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

3
Source Code Evidence Fetched
May 19, 2026 - 14:30 vuln.today
Analysis Generated
May 19, 2026 - 14:30 vuln.today
CVSS changed
May 19, 2026 - 14:22 NVD
10.0 (CRITICAL) 9.5 (CRITICAL)

DescriptionNVD

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.

AnalysisAI

Unauthenticated root-level remote code execution affects HestiaCP versions 1.9.0 through 1.9.4 when the optional web terminal feature is enabled, stemming from a session-handling format mismatch (CWE-502) between the PHP backend and the Node.js web terminal. Remote attackers can inject crafted HTTP header data that PHP writes into session storage but Node.js parses with naive string splitting, yielding arbitrary command execution as root; no public exploit identified at time of analysis, though VulnCheck has published a technical advisory and the upstream patch is publicly diffable.

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RemediationAI

Within 24 hours: Identify all systems running HestiaCP 1.9.0-1.9.4 and determine which have the web terminal feature enabled. Within 7 days: Deploy the vendor patch for CVE-2026-43633 across all affected instances, or disable the web terminal feature as an interim measure. …

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CVE-2026-43633 vulnerability details – vuln.today

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