ConfigServer Security & Firewall: Improper Neutralization of Special Elements used in an OS Command
CVE-2026-65639 is a critical-severity improper neutralization of special elements used in an OS command vulnerability in ConfigServer Security & Firewall from WebPros, with a CVSS 4.0 base score of 9.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 16.30 as the first without the flaw, so updating ConfigServer Security & Firewall to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.42% chance of exploitation within 30 days, higher than 73% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update ConfigServer Security & Firewall to 16.30 or a later version.
- 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 |
|---|---|---|---|
| WebPros | ConfigServer Security & Firewall | 2.15 up to, but not including, 16.30 | 16.30 |
| ConfigServer | ConfigServer Security & Firewall | 2.15 and later | 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.
- Attack requirements
- PresentThe target must be in a specific state or configuration for the attack to work.
- 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:N/AC:L/AT:P/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:X/AU:X/R:X/V:X/RE:X/U:X. Scored by CNA (hackerone.com).
Official description
OS command injection in the advanced-rule parser of ConfigServer Security & Firewall allows a remote attacker who controls a configured allow/deny feed to execute arbitrary commands as root, due to insufficient validation of feed-supplied rule data. The vulnerability affects versions of the software originally distributed by ConfigServer, as well as versions of the WebPros-maintained fork that contain the vulnerable code. WebPros has addressed the vulnerability in version 16.30. Other forks or independently maintained versions of ConfigServer Security & Firewall (CSF) may also be affected and should be evaluated independently.
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 references
Other vulnerabilities in ConfigServer Security & Firewall
- 9.2 Critical severity
- 9.2 Critical severity
Recent Improper Neutralization of Special Elements used in an OS Command vulnerabilities
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 9.8 Critical severity
- 8.8 High severity
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