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CVE Record

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

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.

CriticalCVSS 10Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

HestiaCP 1.9.0 through 1.9.4 has a critical flaw in its web terminal. An unauthenticated internet attacker may be able to execute commands as root if the web terminal is enabled. That means full server takeover is plausible, but the supplied sources do not prove active in-the-wild exploitation.

Executive priority

Immediate remediation is warranted for any exposed HestiaCP server. This is a potential full server compromise without login, so patching or disabling the vulnerable feature should be treated as an emergency operational task.

Technical view

The issue is CWE-502 deserialization in HestiaCP's web terminal path. A PHP and Node.js session format mismatch lets crafted HTTP header data be interpreted as trusted session values by the Node.js component, leading to arbitrary command execution with root-level impact. The CVSS 3.1 score is 10.0.

Likely exposure

Highest concern is internet-reachable HestiaCP installations running 1.9.0 through 1.9.4 with the web terminal feature enabled. Internal-only panels still matter because exploitation requires no authentication once reachable.

Exploitation context

The bundle cites public technical and exploit-oriented references, but KEV is false and no supplied source confirms active exploitation. Treat exposure as urgent because exploitation is remote, unauthenticated, low-complexity, and can compromise confidentiality, integrity, and availability.

Researcher notes

Evidence supports a critical unauthenticated RCE tied to session deserialization across PHP and Node.js in the web terminal. The exact fixed release is not stated in the supplied bundle, but a patch commit and upstream PR are cited. Avoid assuming exploitation beyond public technical availability.

Mitigation direction

  • Apply the HestiaCP vendor patch or a vendor-supported fixed release immediately.
  • Disable the web terminal until remediation is confirmed, if operationally feasible.
  • Restrict HestiaCP panel access to trusted networks or VPN paths.
  • Review HestiaCP issue, pull request, and advisory pages for updated vendor guidance.
  • Prioritize rebuilding or isolating any host suspected of compromise.

Validation and detection

  • Inventory HestiaCP instances and identify versions 1.9.0 through 1.9.4.
  • Confirm whether the web terminal feature is enabled on each instance.
  • Verify the vendor patch or fixed release is installed.
  • Check whether any HestiaCP panel is reachable from the internet.
  • Review relevant logs for suspicious unauthenticated web terminal or session activity.
Prepared
Confidence
high
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · medium confidence lookup

CWE-502: Code execution behavior lookup

Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-43633 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
10 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
3Timeline events
1ADP providers
6Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: yesTechnical Impact: total

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
10CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H3.96VulnCheck
9.5CVSS 4.0CriticalCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H——VulnCheck

Vulnerability scoring details

Base CVSS 4.0 score

9.5Critical
CVSS 4.0 vector shape for CVE-2026-43633Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
hestiacphestiacp1.9.0, 854d71b3c1737b0a0d0cc55c926008ffe1f6719baffected
Weakness

CWE details

CWE-502

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-502 · source CWE mapping

Deserialization of Untrusted Data

Deserialization of Untrusted Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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