Plesk: Improper Neutralization of Special Elements used in an OS Command
CVE-2026-67394 is a critical-severity improper neutralization of special elements used in an OS command vulnerability in Plesk from WebPros, with a CVSS 4.0 base score of 9.0 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists versions 18.0.79.9, 18.0.80.5 as the first without the flaw, so updating Plesk to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.29% chance of exploitation within 30 days, higher than 71% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Plesk to 18.0.79.9 or 18.0.80.5, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| WebPros | Plesk | 18.0.34 up to, but not including, 18.0.79.9; 18.0.80 up to, but not including, 18.0.80.5 | 18.0.79.9, 18.0.80.5 |
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
- LowA basic user account is enough.
- 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:L/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
A critical local privilege escalation via OS command injection vulnerability has been discovered in Plesk for Linux, affecting all versions from 18.0.34 before 18.0.79.9 and 18.0.80.5. The vulnerability allows a customer or reseller with shell access (or allowed to change their own shell access) to elevate privileges to the root account on the hosting server.
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).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in Plesk
- 8.4 High severity
- 8.7 High severity
- 9.9 Critical severity
- 9.9 Critical severity
- 8.6 High severity
- 9.3 Critical severity
Recent Improper Neutralization of Special Elements used in an OS Command vulnerabilities
- 7.8 High severity
- 7.7 High severity
- 7.2 High severity
- 8.8 High severity
- 7.2 High severity
- 7.2 High severity
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