nuclei: Improper Neutralization of Special Elements used in an OS Command
CVE-2024-40641 is a high-severity improper neutralization of special elements used in an OS command vulnerability in nuclei from ProjectDiscovery, with a CVSS 3.1 base score of 7.4 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version 3.3.0 as the first without the flaw, so updating nuclei to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.31% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update nuclei to 3.3.0 or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Projectdiscovery | nuclei | >= 3.0.0, < 3.3.0; 3.0.0 up to, but not including, 3.3.0 | 3.3.0 |
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
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- 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
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N. Scored by CNA (github.com).
Official description
Nuclei is a fast and customizable vulnerability scanner based on simple YAML based DSL. In affected versions it a way to execute code template without -code option and signature has been discovered. Some web applications inherit from Nuclei and allow users to edit and execute workflow files. In this case, users can execute arbitrary commands. (Although, as far as I know, most web applications use -t to execute). This issue has been addressed in version 3.3.0. Users are advised to upgrade. There are no known workarounds for this vulnerability.
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: poc, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in nuclei
- 7.3 High severity
- 7.5 High severity
- 7.8 High severity
- 7.4 High severity
- 7.5 High severity
Recent Improper Neutralization of Special Elements used in an OS Command vulnerabilities
- 9.8 Critical severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
Spotted an error? Tell us.