CVE-2026-43633 | THREATINT

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.

PUBLISHED Reserved 2026-05-01 | Published 2026-05-19 | Updated 2026-05-19 | Assigner VulnCheck

CRITICAL: 9.5CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

CRITICAL: 10.0CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Problem types

Deserialization of Untrusted Data

Product status

Default status
affected

1.9.0 (semver)
affected

854d71b3c1737b0a0d0cc55c926008ffe1f6719b (git)
unaffected

Credits

sutol finder

divinity76 finder

References

mercuryiss.com.au/…-spoofing-cve-2026-43633-cve-2026-43634 issue-tracking

github.com/hestiacp/hestiacp/issues/5229 issue-tracking

github.com/hestiacp/hestiacp/pull/5244 patch

github.com/…ommit/854d71b3c1737b0a0d0cc55c926008ffe1f6719b

www.vulncheck.com/…cp-deserialization-rce-via-web-terminal third-party-advisory

cve.org (CVE-2026-43633)

nvd.nist.gov (CVE-2026-43633)

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