VSFF6: Improper Neutralization of Special Elements used in an OS Command
CVE-2026-95377 is a critical-severity improper neutralization of special elements used in an OS command vulnerability in VSFF6 from Zenitel, with a CVSS 4.0 base score of 9.4 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists versions 9.6.3.0, 10.1.3.0 as the first without the flaw, so updating VSFF6 to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.21% chance of exploitation within 30 days, higher than 69% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update VSFF6 to 9.6.3.0 or 10.1.3.0, whichever matches your release line, or a later version.
- Update VSFF8 to 9.6.3.0 or 10.1.3.0, whichever matches your release line, or a later version.
- Update VSFF8MP to 9.6.3.0 or 10.1.3.0, whichever matches your release line, or a later version.
- Read the advisory on zenitel.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Zenitel | VSFF6 | before 9.6.3.0; 10.0.0.0 up to, but not including, 10.1.3.0 | 9.6.3.0, 10.1.3.0 |
| Zenitel | VSFF8 | before 9.6.3.0; 10.0.0.0 up to, but not including, 10.1.3.0 | 9.6.3.0, 10.1.3.0 |
| Zenitel | VSFF8MP | before 9.6.3.0; 10.0.0.0 up to, but not including, 10.1.3.0 | 9.6.3.0, 10.1.3.0 |
| Zenitel | VSFF8MN | before 9.6.3.0; 10.0.0.0 up to, but not including, 10.1.3.0 | 9.6.3.0, 10.1.3.0 |
| Zenitel | VSFT | before 9.6.3.0; 10.0.0.0 up to, but not including, 10.1.3.0 | 9.6.3.0, 10.1.3.0 |
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
- AdjacentThe attacker must be on the same local network segment.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Attack requirements
- NoneThe attack does not depend on a particular deployment or configuration.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Confidentiality (vulnerable system)
- HighSerious loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- HighSerious loss of integrity on the vulnerable system.
- Availability (vulnerable system)
- HighSerious loss of availability on the vulnerable system.
- Confidentiality (other systems)
- HighSerious loss of confidentiality on systems beyond the vulnerable one.
- Integrity (other systems)
- HighSerious loss of integrity on systems beyond the vulnerable one.
- Availability (other systems)
- HighSerious loss of availability on systems beyond the vulnerable one.
Vector: CVSS:4.0/AV:A/AC:L/AT:N/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:P/AU:Y/R:X/V:X/RE:X/U:X. Scored by CNA.
Official description
OS command injection in the TFTP provisioning module of Zenitel EdgeAudioClient before 9.6.3.0, and 10.x before 10.1.3.0, on VSFF6, VSFF8, VSFF8MP, VSFF8MN, and VSFT devices allows unauthenticated adjacent attackers to execute arbitrary commands as root via a crafted DHCP option 66 (TFTP Server Name) value supplied by a rogue DHCP server on the same network segment. The DHCP-supplied value is passed to a shell without sanitization. Devices using DHCP, the default configuration, are affected on every boot and lease renewal. The same injection is also reachable via the config_update_tftp_server and sw_update_tftp_server configuration fields by an attacker able to modify the device configuration.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Special Elements used in an OS Command
The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command before it is sent to a downstream component.
How developers prevent this class of flaw
- If at all possible, use library calls rather than external processes to recreate the desired functionality.
- For any data that will be used to generate a command to be executed, keep as much of that data out of external control as possible. For example, in web applications, this may require storing the data locally in the session's state instead of sending it out to the client in a hidden form field.
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
More Improper Neutralization of Special Elements used in an OS Command vulnerabilities (CWE-78)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
References
Other vulnerabilities in VSFF6
- 7.0 High severity
- 8.6 High severity
Recent Improper Neutralization of Special Elements used in an OS Command vulnerabilities
- 8.7 High severity
- 7.8 High severity
- 8.1 High severity
- 8.7 High severity
- 9.1 Critical severity
- 8.8 High severity
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