# CVE-2017-3849: Denial of service in Cisco IOS and IOS XE

> An unauthenticated adjacent attacker can cause a denial of service by sending crafted packets to a Cisco IOS device configured as an autonomic registrar with a whitelist.

- **Severity:** High 7.4 (`CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 Mar 2017
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-3h7c-9m67-pxx8

## What is CVE-2017-3849?

CVE-2017-3849 is a high-severity denial of service vulnerability in Cisco Ios, published on 21 Mar 2017. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in the Autonomic Networking Infrastructure (ANI) registrar feature of Cisco IOS Software (possibly 15.2 through 15.6) and Cisco IOS XE Software (possibly 3.7 through 3.18, and 16) could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition. The vulnerability is due to incomplete input validation on certain crafted packets. An attacker could exploit this vulnerability by sending a crafted autonomic network channel discovery packet to a device that has all the following characteristics: (1) running a Cisco IOS Software or Cisco IOS XE Software release that supports the ANI feature; (2) configured as an autonomic registrar; (3) has a whitelist configured. An exploit could allow the attacker to cause the affected device to reload. Note: Autonomic networking should be configured with a whitelist. Do not remove the whitelist as a workaround. Cisco Bug IDs: CSCvc42717.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2017-3849?

It affects 2 products.


Products: Cisco Ios, Cisco Ios Xe.

## How do I fix CVE-2017-3849?

No fix has been published for CVE-2017-3849 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-3849 being exploited?

There is no known exploitation of CVE-2017-3849 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Ios

- [CVE-2017-12240](https://insights.sbomify.com/CVE-2017-12240/): Cisco IOS and IOS XE Software DHCP Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2017-3881](https://insights.sbomify.com/CVE-2017-3881/): Cisco IOS and IOS XE Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2018-0167](https://insights.sbomify.com/CVE-2018-0167/): Cisco IOS, XR, and XE Software Buffer Overflow (high 8.8, exploited in the wild)
- [CVE-2017-6736](https://insights.sbomify.com/CVE-2017-6736/): Cisco IOS and IOS XE Software SNMP Remote Code Execution (high 8.8, exploited in the wild)
- [CVE-2017-6737](https://insights.sbomify.com/CVE-2017-6737/): Cisco IOS and IOS XE Software SNMP Remote Code Execution (high 8.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-3849 and fix it if it is affected.

What it is: CVE-2017-3849 is a high-severity denial of service vulnerability in Cisco Ios, published on 21 Mar 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-2017-3849 in the wild and no public exploit code.

Affected product: Cisco Ios. 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-2017-3849/ (Markdown: https://insights.sbomify.com/CVE-2017-3849/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-3849
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-3849
- OSV: https://osv.dev/vulnerability/CVE-2017-3849

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From sbomify Insights: https://insights.sbomify.com/CVE-2017-3849/
Summaries are generated and may contain mistakes; the official description above is the record.