# CVE-2024-20327: Denial of service in Cisco IOS XR Software

> An unauthenticated adjacent attacker can crash the PPPoE process on Cisco ASR 9000 routers by sending malformed packets, causing a denial of service.

- **Severity:** High 7.4 (`CVSS:3.1/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:** 13 Mar 2024
- **Updated:** 1 Aug 2024
- **Also known as:** GHSA-2295-7pf8-fmwg

## What is CVE-2024-20327?

CVE-2024-20327 is a high-severity denial of service vulnerability in Cisco Ios Xr, published on 13 Mar 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 PPP over Ethernet (PPPoE) termination feature of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers could allow an unauthenticated, adjacent attacker to crash the ppp_ma process, resulting in a denial of service (DoS) condition.

 This vulnerability is due to the improper handling of malformed PPPoE packets that are received on a router that is running Broadband Network Gateway (BNG) functionality with PPPoE termination on a Lightspeed-based or Lightspeed-Plus-based line card. An attacker could exploit this vulnerability by sending a crafted PPPoE packet to an affected line card interface that does not terminate PPPoE. A successful exploit could allow the attacker to crash the ppp_ma process, resulting in a DoS condition for PPPoE traffic across the router.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2024-20327?

It affects 1 product.


Products: Cisco Ios Xr.

## How do I fix CVE-2024-20327?

No fix has been published for CVE-2024-20327 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-20327 being exploited?

There is no known exploitation of CVE-2024-20327 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-2024-20327 and fix it if it is affected.

What it is: CVE-2024-20327 is a high-severity denial of service vulnerability in Cisco Ios Xr, published on 13 Mar 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-2024-20327 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-2024-20327/ (Markdown: https://insights.sbomify.com/CVE-2024-20327/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-20327
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-20327
- OSV: https://osv.dev/vulnerability/CVE-2024-20327

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-20327/
Summaries are generated and may contain mistakes; the official description above is the record.