nuclei: Improper Neutralization of Special Elements used in an OS Command
CVE-2024-43405 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 7.8 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 3.3.2 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 1.11% chance of exploitation within 30 days, higher than 66% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update nuclei to 3.3.2 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, < 3.3.2; 3.0.0 up to, but not including, 3.3.2 | 3.3.2 |
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
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- 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:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.4 | High | CNA (github.com) |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
Nuclei is a vulnerability scanner powered by YAML based templates. Starting in version 3.0.0 and prior to version 3.3.2, a vulnerability in Nuclei's template signature verification system could allow an attacker to bypass the signature check and possibly execute malicious code via custom code template. The vulnerability is present in the template signature verification process, specifically in the `signer` package. The vulnerability stems from a discrepancy between how the signature verification process and the YAML parser handle newline characters, combined with the way multiple signatures are processed. This allows an attacker to inject malicious content into a template while maintaining a valid signature for the benign part of the template. CLI users are affected if they execute custom code templates from unverified sources. This includes templates authored by third parties or obtained from unverified repositories. SDK Users are affected if they are developers integrating Nuclei into their platforms, particularly if they permit the execution of custom code templates by end-users. The vulnerability is addressed in Nuclei v3.3.2. Users are strongly recommended to update to this version to mitigate the security risk. As an interim measure, users should refrain from using custom templates if unable to upgrade immediately. Only trusted, verified templates should be executed. Those who are unable to upgrade Nuclei should disable running custom code templates as a workaround.
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
Advisories
- github.com/projectdiscovery/nuclei/security/advisories/GHSA-7h5p-mmpp-hgmmMitigation, Third Party Advisory
Patches and release notes
Other vulnerabilities in nuclei
- 7.3 High severity
- 7.5 High severity
- 7.4 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
- 7.2 High severity
- 7.2 High severity
- 7.2 High severity
- 8.1 High severity
- 9.8 Critical severity
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