GV-VMS V20.0.2: Out-of-bounds Write
CVE-2026-42369 is a critical-severity out-of-bounds write vulnerability in GV-VMS V20.0.2 from GeoVision, with a CVSS 3.1 base score of 10.0 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected GV-VMS V20.0.2 versions: V20.0.2. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.54% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of GV-VMS V20.0.2 you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| GeoVision | GV-VMS V20.0.2 | V20.0.2 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H. Scored by CNA.
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in GV-VMS V20.0.2
- 9.0 Critical severity
- 9.8 Critical severity
Recent Out-of-bounds Write vulnerabilities
- 7.5 High severity
- 7.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
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