# CVE-2019-1836: Path traversal in Cisco NX-OS Software for Nexus 9000 Series Fabric Switches ACI Mode

> Authenticated local attackers can overwrite restricted system files via symbolic links in the CLI, potentially escalating privileges on Cisco Nexus switches.

- **Severity:** Medium 5.5 (`CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 May 2019
- **Updated:** 21 Nov 2024
- **Also known as:** GHSA-3pmp-7vwx-87p3

## What is CVE-2019-1836?

CVE-2019-1836 is a medium-severity path traversal vulnerability in Cisco Nx-Os, published on 3 May 2019. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in the system shell for Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode could allow an authenticated, local attacker to use symbolic links to overwrite system files. These system files may be sensitive and should not be overwritable by non-root users. The attacker would need valid device credentials. The vulnerability is due to incorrect symbolic link verification of directory paths when they are used in the system shell. An attacker could exploit this vulnerability by authenticating to the device and providing crafted user input to specific symbolic link CLI commands. Successful exploitation could allow the attacker to overwrite system files that should be restricted. This vulnerability has been fixed in software version 14.1(1i).

Weakness: CWE-59 (Improper Link Resolution Before File Access), CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2019-1836?

It affects 1 product.


Products: Cisco Nx-Os.

## How do I fix CVE-2019-1836?

No fix has been published for CVE-2019-1836 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-1836 being exploited?

There is no known exploitation of CVE-2019-1836 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Nx-Os

- [CVE-2024-20399](https://insights.sbomify.com/CVE-2024-20399/): Cisco NX-OS Command Injection (medium 6.0, exploited in the wild)
- [CVE-2021-1361](https://insights.sbomify.com/CVE-2021-1361/): Cisco NX-OS Software Unauthenticated Arbitrary File Actions Vulnerability (critical 9.8)
- [CVE-2018-0301](https://insights.sbomify.com/CVE-2018-0301/): Memory corruption in Cisco NX-OS unknown (critical 9.8)
- [CVE-2016-1453](https://insights.sbomify.com/CVE-2016-1453/): Memory corruption in n/a (critical 9.8)
- [CVE-2016-1341](https://insights.sbomify.com/CVE-2016-1341/): Hardcoded credentials in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-1836 and fix it if it is affected.

What it is: CVE-2019-1836 is a medium-severity path traversal vulnerability in Cisco Nx-Os, published on 3 May 2019. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-1836 in the wild and no public exploit code.

Affected product: Cisco Nx-Os. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2019-1836/ (Markdown: https://insights.sbomify.com/CVE-2019-1836/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-1836
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-1836
- OSV: https://osv.dev/vulnerability/CVE-2019-1836

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-1836/
Summaries are generated and may contain mistakes; the official description above is the record.