# CVE-2022-20849: Cisco IOS XR Software Broadband Network Gateway PPPoE Denial of Service Vulnerability

> An unauthenticated adjacent attacker can cause a denial of service by sending crafted PPPoE packets to Cisco IOS XR devices.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:A/AC:H/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:** 15 Nov 2024
- **Updated:** 15 Nov 2024
- **Also known as:** GHSA-r2p4-pwjj-hqr4

## What is CVE-2022-20849?

CVE-2022-20849 is a medium-severity denial of service vulnerability in Cisco Ios Xr, published on 15 Nov 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in the Broadband Network Gateway PPP over Ethernet (PPPoE) feature of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause the PPPoE process to continually crash.
This vulnerability exists because the PPPoE feature does not properly handle an error condition within a specific crafted packet sequence. An attacker could exploit this vulnerability by sending a sequence of specific PPPoE packets from controlled customer premises equipment (CPE). A successful exploit could allow the attacker to cause the PPPoE process to continually restart, resulting in a denial of service condition (DoS).Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.This advisory is part of the September 2022 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see .

Weakness: CWE-391 (DEPRECATED: Unchecked Error Condition)

## Which versions are affected by CVE-2022-20849?

It affects 1 product.


Products: Cisco Ios Xr.

## How do I fix CVE-2022-20849?

No fix has been published for CVE-2022-20849 yet. Limit exposure of the affected software until one is available.

## Is CVE-2022-20849 being exploited?

There is no known exploitation of CVE-2022-20849 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Ios Xr

- [CVE-2020-3118](https://insights.sbomify.com/CVE-2020-3118/): Cisco IOS XR Software Discovery Protocol Format String (high 8.8, exploited in the wild)
- [CVE-2020-3569](https://insights.sbomify.com/CVE-2020-3569/): Cisco IOS XR Software DVMRP Memory Exhaustion (high 8.6, exploited in the wild)
- [CVE-2020-3566](https://insights.sbomify.com/CVE-2020-3566/): Cisco IOS XR Software DVMRP Memory Exhaustion (high 8.6, exploited in the wild)
- [CVE-2010-3035](https://insights.sbomify.com/CVE-2010-3035/): Cisco IOS XR Border Gateway Protocol (BGP) Denial-of-Service (high 7.5, exploited in the wild)
- [CVE-2022-20821](https://insights.sbomify.com/CVE-2022-20821/): Cisco IOS XR Open Port (medium 6.5, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-20849 and fix it if it is affected.

What it is: CVE-2022-20849 is a medium-severity denial of service vulnerability in Cisco Ios Xr, published on 15 Nov 2024. 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-2022-20849 in the wild and no public exploit code.

Affected product: Cisco Ios Xr. 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-2022-20849/ (Markdown: https://insights.sbomify.com/CVE-2022-20849/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-20849
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-20849
- OSV: https://osv.dev/vulnerability/CVE-2022-20849

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From sbomify Insights: https://insights.sbomify.com/CVE-2022-20849/
Summaries are generated and may contain mistakes; the official description above is the record.