Cisco IOS: Improper Limitation of a Pathname to a Restricted Directory
CVE-2022-20719 is a high-severity improper limitation of a pathname to a restricted directory vulnerability in Cisco IOS from Cisco, with a CVSS 3.1 base score of 7.2 out of 10. It can be exploited remotely over the network by an attacker with administrator privileges, without any action from a user. There is no confirmed exploitation so far. EPSS estimates a 2.7% chance of exploitation within 30 days, higher than 86% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Cisco IOS you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cisco | Cisco IOS | Not specified in the record | Not stated |
| Cisco | iOS Xe | 16.3.1; 16.3.1a; 16.3.2; 16.3.3; 16.3.4; 16.3.5; 16.3.5b; 16.3.6; and 32 more ranges | Not stated |
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
- HighAdministrator-level access is required first.
- 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
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 5.5 | Medium | CNA (cisco.com) |
| CVSS 3.1 | 7.2 | High | NVD |
| CVSS 2.0 | 9.0 | High | NVD |
Official description
Multiple vulnerabilities in the Cisco IOx application hosting environment on multiple Cisco platforms could allow an attacker to inject arbitrary commands into the underlying host operating system, execute arbitrary code on the underlying host operating system, install applications without being authenticated, or conduct a cross-site scripting (XSS) attack against a user of the affected software. For more information about these vulnerabilities, see the Details section of this advisory.
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.
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in Cisco IOS
- 7.5 High severity
- 8.8 High severity
- 7.7 High severity
- 7.5 High severity
- 7.5 High severity
- 7.2 High severity
Recent Improper Limitation of a Pathname to a Restricted Directory vulnerabilities
- 8.8 High severity
- 7.5 High severity
- 8.0 High severity
- 7.8 High severity
- 9.1 Critical severity
- 7.5 High severity
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