# CVE-2013-6979: Auth bypass in n/a

> Remote attackers can bypass VTY authentication in Cisco IOS XE by leveraging specific internal IP configurations, requiring vendor patches.

- **Severity:** Medium 5.4 (`AV:N/AC:H/Au:N/C:C/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 23 Dec 2013
- **Updated:** 6 Aug 2024
- **Also known as:** GHSA-rvr7-79c9-w4jr

## What is CVE-2013-6979?

CVE-2013-6979 is a medium-severity authentication bypass vulnerability in Cisco Ios Xe, published on 23 Dec 2013. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The VTY authentication implementation in Cisco IOS XE 03.02.xxSE and 03.03.xxSE incorrectly relies on the Linux-IOS internal-network configuration, which allows remote attackers to bypass authentication by leveraging access to a 192.168.x.2 source IP address, aka Bug ID CSCuj90227.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2013-6979?

It affects 1 product.


Products: Cisco Ios Xe.

## How do I fix CVE-2013-6979?

No fix has been published for CVE-2013-6979 yet. Limit exposure of the affected software until one is available.

## Is CVE-2013-6979 being exploited?

There is no known exploitation of CVE-2013-6979 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Ios Xe

- [CVE-2023-20198](https://insights.sbomify.com/CVE-2023-20198/): Cisco IOS XE Web UI Privilege Escalation (critical 10.0, exploited in the wild)
- [CVE-2018-0151](https://insights.sbomify.com/CVE-2018-0151/): Cisco IOS Software and Cisco IOS XE Software Quality of Service Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2023-20273](https://insights.sbomify.com/CVE-2023-20273/): Cisco IOS XE Web UI Command Injection (high 7.2, exploited in the wild)
- [CVE-2025-20188](https://insights.sbomify.com/CVE-2025-20188/): Hardcoded credentials in Cisco IOS XE Software (critical 10.0)
- [CVE-2021-34770](https://insights.sbomify.com/CVE-2021-34770/): Cisco IOS XE Software for Catalyst 9000 Family Wireless Controllers CAPWAP Remote Code Execution Vulnerability (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2013-6979 and fix it if it is affected.

What it is: CVE-2013-6979 is a medium-severity authentication bypass vulnerability in Cisco Ios Xe, published on 23 Dec 2013. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2013-6979 in the wild and no public exploit code.

Affected product: Cisco Ios Xe. 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-2013-6979/ (Markdown: https://insights.sbomify.com/CVE-2013-6979/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2013-6979
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2013-6979
- OSV: https://osv.dev/vulnerability/CVE-2013-6979

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From sbomify Insights: https://insights.sbomify.com/CVE-2013-6979/
Summaries are generated and may contain mistakes; the official description above is the record.