Docutils: Improper Limitation of a Pathname to a Restricted Directory
CVE-2022-23602 is a high-severity improper limitation of a pathname to a restricted directory vulnerability in Docutils from Nim-lang, with a CVSS 3.1 base score of 8.1 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 version 1.6.2 as the first without the flaw, so updating Docutils to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.34% chance of exploitation within 30 days, higher than 72% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Docutils to 1.6.2 or a later version.
- Update Nimforum to 2.2.0 or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Nim-lang | Docutils | before 1.6.2 | 1.6.2 |
| Nim-lang | Nimforum | before 2.2.0 | 2.2.0 |
Version data comes from NVD's product matching. 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
- LowA basic user account is enough.
- 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
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.7 | High | CNA (github.com) |
| CVSS 3.1 | 8.1 | High | NVD |
| CVSS 2.0 | 5.5 | Medium | NVD |
Official description
Nimforum is a lightweight alternative to Discourse written in Nim. In versions prior to 2.2.0 any forum user can create a new thread/post with an include referencing a file local to the host operating system. Nimforum will render the file if able. This can also be done silently by using NimForum's post "preview" endpoint. Even if NimForum is running as a non-critical user, the forum.json secrets can be stolen. Version 2.2.0 of NimForum includes patches for this vulnerability. Users are advised to upgrade as soon as is possible. There are no known workarounds for this issue.
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: poc, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/nim-lang/nimforum/security/advisories/GHSA-q3vh-x957-wr75Exploit, Third Party Advisory
Patches and release notes
- github.com/nim-lang/Nim/commit/cb894c7094fb49014f85815a9dafc38b5dda743eThird Party Advisory
Recent Improper Limitation of a Pathname to a Restricted Directory vulnerabilities
- 9.8 Critical severity
- 7.5 High severity
- 7.5 High severity
- 8.1 High severity
- 7.8 High severity
- 5.0 Medium severity
Grafana Path Traversal Exploited
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