# CVE-2019-1846: Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers MPLS OAM Denial of Service Vulnerability

> An unauthenticated adjacent attacker can cause a denial of service on Cisco ASR 9000 routers by sending malicious MPLS OAM packets.

- **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:** 16 May 2019
- **Updated:** 21 Nov 2024
- **Also known as:** GHSA-554h-cqv3-h79q

## What is CVE-2019-1846?

CVE-2019-1846 is a high-severity denial of service vulnerability in Cisco Ios Xr, published on 16 May 2019. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in the Multiprotocol Label Switching (MPLS) Operations, Administration, and Maintenance (OAM) implementation of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers could allow an unauthenticated, adjacent attacker to trigger a denial of service (DoS) condition on an affected device. The vulnerability is due to the incorrect handling of certain MPLS OAM packets. An attacker could exploit this vulnerability by sending malicious MPLS OAM packets to an affected device. A successful exploit could allow the attacker to cause the lspv_server process to crash. The crash could lead to system instability and the inability to process or forward traffic though the device, resulting in a DoS condition that require manual intervention to restore normal operating conditions.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2019-1846?

It affects 1 product.


Products: Cisco Ios Xr.

## How do I fix CVE-2019-1846?

No fix has been published for CVE-2019-1846 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-1846 being exploited?

There is no known exploitation of CVE-2019-1846 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-2019-1846 and fix it if it is affected.

What it is: CVE-2019-1846 is a high-severity denial of service vulnerability in Cisco Ios Xr, published on 16 May 2019. 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-2019-1846 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-2019-1846/ (Markdown: https://insights.sbomify.com/CVE-2019-1846/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-1846
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-1846
- OSV: https://osv.dev/vulnerability/CVE-2019-1846

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-1846/
Summaries are generated and may contain mistakes; the official description above is the record.