nuclei: Improper Limitation of a Pathname to a Restricted Directory
CVE-2023-37896 is a high-severity improper limitation of a pathname to a restricted directory vulnerability in nuclei from ProjectDiscovery, with a CVSS 3.1 base score of 7.5 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 2.9.9 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 1.05% chance of exploitation within 30 days, higher than 65% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update nuclei to 2.9.9 or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- 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 |
|---|---|---|---|
| Projectdiscovery | nuclei | < 2.9.9; before 2.9.9 | 2.9.9 |
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.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | CNA (github.com) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
Nuclei is a vulnerability scanner. Prior to version 2.9.9, a security issue in the Nuclei project affected users utilizing Nuclei as Go code (SDK) running custom templates. This issue did not affect CLI users. The problem was related to sanitization issues with payload loading in sandbox mode. There was a potential risk with payloads loading in sandbox mode. The issue occurred due to relative paths not being converted to absolute paths before doing the check for `sandbox` flag allowing arbitrary files to be read on the filesystem in certain cases when using Nuclei from `Go` SDK implementation. This issue has been fixed in version 2.9.9. The maintainers have also enabled sandbox by default for filesystem loading. This can be optionally disabled if required. The `-sandbox` option has been deprecated and is now divided into two new options: `-lfa` (allow local file access) which is enabled by default and `-lna` (restrict local network access) which can be enabled by users optionally. The `-lfa` allows file (payload) access anywhere on the system (disabling sandbox effectively), and `-lna` blocks connections to the local/private network.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Limitation of a Pathname to a Restricted Directory
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
How developers prevent this class of flaw
- 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.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.
More Improper Limitation of a Pathname to a Restricted Directory vulnerabilities (CWE-22)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- github.com/projectdiscovery/nuclei/pull/3927Issue Tracking
- github.com/projectdiscovery/nuclei/releases/tag/v2.9.9Release Notes
Other vulnerabilities in nuclei
- 7.3 High severity
- 7.5 High severity
- 7.8 High severity
- 7.4 High severity
- 7.4 High severity
Recent Improper Limitation of a Pathname to a Restricted Directory vulnerabilities
- 8.8 High severity
- 9.8 Critical severity
- 8.8 High severity
- 9.8 Critical severity
- 7.5 High severity
ZKTeco BioTime Path Traversal Exploited
- 7.5 High severity
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