# CVE-2023-20049: Cisco IOS XR Software for ASR 9000 Series Routers Bidirectional Forwarding Detection Denial of Service Vulnerability

> Remote attackers can cause line card resets and traffic loss on Cisco ASR 9000 routers by sending crafted BFD packets when hardware offload is enabled.

- **Severity:** High 8.6 (`CVSS:3.1/AV:N/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:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Mar 2023
- **Updated:** 28 Oct 2024
- **Also known as:** GHSA-3q76-jpjg-96ff

## What is CVE-2023-20049?

CVE-2023-20049 is a high-severity denial of service vulnerability in Cisco Ios Xr, published on 9 Mar 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the bidirectional forwarding detection (BFD) hardware offload feature of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers, ASR 9902 Compact High-Performance Routers, and ASR 9903 Compact High-Performance Routers could allow an unauthenticated, remote attacker to cause a line card to reset, resulting in a denial of service (DoS) condition. This vulnerability is due to the incorrect handling of malformed BFD packets that are received on line cards where the BFD hardware offload feature is enabled. An attacker could exploit this vulnerability by sending a crafted IPv4 BFD packet to an affected device. A successful exploit could allow the attacker to cause line card exceptions or a hard reset, resulting in loss of traffic over that line card while the line card reloads.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), CWE-805 (Buffer Access with Incorrect Length Value)

## Which versions are affected by CVE-2023-20049?

It affects 1 product.


Products: Cisco Ios Xr.

## How do I fix CVE-2023-20049?

No fix has been published for CVE-2023-20049 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-20049 being exploited?

There is no known exploitation of CVE-2023-20049 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-2023-20049 and fix it if it is affected.

What it is: CVE-2023-20049 is a high-severity denial of service vulnerability in Cisco Ios Xr, published on 9 Mar 2023. 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-2023-20049 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-2023-20049/ (Markdown: https://insights.sbomify.com/CVE-2023-20049/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-20049
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-20049
- OSV: https://osv.dev/vulnerability/CVE-2023-20049

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-20049/
Summaries are generated and may contain mistakes; the official description above is the record.