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Out-of-bounds WriteWeakness · CWE-787

CVE-2026-42369

CRITICAL · 10.0 CVSS v3.1 Published 2026-05-04
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
GV-VMS V20 is a Video Monitoring Software used to gather the feeds of many surveillance cameras and manage other security devices. It is a native application accessed locally, but it is also possible to enable remote access via the "WebCam Server" feature. Once enabled, it is possible to access to the management and monitoring feature via a regular Web interface. This webersever is another native application, compiled without ASLR, which makes exploitation much easier and more likely. Most of the features require authentication before being reachable and leverage a standard login page to grant access. However the `gvapi` endpoint uses its own authentication mechanism via an `HTTP Authorization` header. It supports both `Basic` authentication and the `Digest` modes of authentication.   #### Stack-overflow via unbound copy of base64 decoded string The `b64decoder` string is sized dynamically, but it is then copied to the `Buffer` stack variable one character at the time at [0], and there's no bound-check. As such, if the decoded string is bigger than 256 characters (the size of the `Buffer` variable) then a stack overflow occurs. Because the data can be fully controlled by an attacker and lack of ASLR, this vulnerability can easily be exploited to gain full code execution as SYSTEM on the machine running the service.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Stack-based buffer overflow in GV-VMS V20 WebCam Server's gvapi endpoint. The base64-decoded authorization string is copied to a fixed 256-byte stack buffer without bounds checking, allowing overflow when decoded string exceeds 256 characters. The service runs as SYSTEM and the binary lacks ASLR, enabling trivial remote code execution.

MitigationDisable the WebCam Server feature if not required; apply vendor patch when available; if WebCam Server is required, isolate the service via network segmentation and restrict access to trusted IPs only.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify GV-VMS V20 installation and version
    Locate the GV-VMS installation directory (commonly C:\Program Files\GeoVision\GV-VMS or C:\GeoVision\GV-VMS). Check for the main executable (GV-VMS.exe or VMSWebServer.exe) and right-click to view Properties > Details for the File Version.
    Affected if GV-VMS V20.x is installed and the version falls within the affected range (any V20 version prior to patch).
  2. Confirm WebCam Server service is running
    Open Services (services.msc) and look for a service named 'GV VMS WebCam Server' or 'WebCam Server'. Check the Status column; if it shows 'Running', the vulnerable component is active.
    Affected if The WebCam Server service is running and listening on network ports (default 8088, 8089, or 80).
  3. Identify the gvapi endpoint exposure
    Open Command Prompt and run 'netstat -ano | findstr LISTENING' to list listening ports. Look for ports associated with the WebCam Server (often 8088, 8089). Use a browser or curl to access http://localhost:PORT/gvapi and verify the endpoint responds.
    Affected if The gvapi endpoint is accessible over the network (not localhost-only) and accepts authorization headers.
  4. Check service account privileges
    In Services, right-click the WebCam Server service > Properties > Log On tab. Verify the account listed is not 'Local System account' or 'SYSTEM'.
    Affected if The service runs under Local System account or SYSTEM, meaning it has highest privileges.
  5. Verify binary ASLR protection
    Navigate to the WebCam Server binary location (e.g., in the GV-VMS installation folder). Use dumpbin /headers or a tool like PE Explorer to check the DLL Characteristics field. Look for 'DYNAMIC_BASE' flag indicating ASLR is enabled.
    Affected if The binary lacks ASLR (DYNAMIC_BASE flag not set), making exploitation reliable.

If GV-VMS V20 is installed with WebCam Server running as SYSTEM and the gvapi endpoint is network-accessible, the system is vulnerable to this buffer overflow.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Disable the WebCam Server feature if not required; apply vendor patch when available; if WebCam Server is required, isolate the service via network segmentation and restrict access to trusted IPs only.

Have this fixed Scoped from the published advisory
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  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,150
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-42369 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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