# CVE-2017-12340: Security feature bypass in Cisco Multilayer Director, Nexus 7000 Series, and Nexus 7700 Series Switches

> Authenticated local attackers can bypass Bash shell restrictions and execute arbitrary commands via Python sandbox escape on Cisco switches.

- **Severity:** Medium 4.2 (`CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 30 Nov 2017
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-7fgx-h5gw-66x7

## What is CVE-2017-12340?

CVE-2017-12340 is a medium-severity vulnerability in Cisco Nx-Os, published on 30 Nov 2017. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in Cisco NX-OS System Software running on Cisco MDS Multilayer Director Switches, Cisco Nexus 7000 Series Switches, and Cisco Nexus 7700 Series Switches could allow an authenticated, local attacker to access the Bash shell of an affected device's operating system, even if the Bash shell is disabled on the system. The vulnerability is due to insufficient sanitization of user-supplied parameters that are passed to certain functions of the Python scripting sandbox of the affected system. An attacker could exploit this vulnerability to escape the scripting sandbox and enter the Bash shell of the operating system with the privileges of the authenticated user for the affected system. To exploit this vulnerability, the attacker must have local access to the affected system and be authenticated to the affected system with administrative or Python execution privileges. Cisco Bug IDs: CSCvd86513.

Weakness: CWE-116 (Improper Encoding or Escaping of Output), CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2017-12340?

It affects 1 product.


Products: Cisco Nx-Os.

## How do I fix CVE-2017-12340?

No fix has been published for CVE-2017-12340 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-12340 being exploited?

There is no known exploitation of CVE-2017-12340 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-2017-12340 and fix it if it is affected.

What it is: CVE-2017-12340 is a medium-severity vulnerability in Cisco Nx-Os, published on 30 Nov 2017. 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-2017-12340 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-2017-12340/ (Markdown: https://insights.sbomify.com/CVE-2017-12340/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-12340
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-12340
- OSV: https://osv.dev/vulnerability/CVE-2017-12340

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-12340/
Summaries are generated and may contain mistakes; the official description above is the record.