# CVE-2019-16018: Cisco IOS XR Software EVPN Operational Routes Denial of Service Vulnerability

> Remote attackers can cause a denial of service in Cisco IOS XR by sending malformed BGP EVPN messages, requiring a valid peer connection.

- **Severity:** High 7.4 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:R/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:** A user has to click or open something
- **Fix available:** No
- **Published:** 26 Jan 2020
- **Updated:** 15 Nov 2024
- **Also known as:** GHSA-638h-mp9x-p4wm

## What is CVE-2019-16018?

CVE-2019-16018 is a high-severity denial of service vulnerability in Cisco Ios Xr, published on 26 Jan 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

A vulnerability in the implementation of Border Gateway Protocol (BGP) Ethernet VPN (EVPN) functionality in Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to incorrect processing of a BGP update message that contains crafted EVPN attributes. An attacker could indirectly exploit the vulnerability by sending BGP EVPN update messages with a specific, malformed attribute to an affected system and waiting for a user on the device to display the EVPN operational routes’ status. If successful, the attacker could cause the BGP process to restart unexpectedly, resulting in a DoS condition. The Cisco implementation of BGP accepts incoming BGP traffic only from explicitly defined peers. To exploit this vulnerability, the malicious BGP update message would need to come from a configured, valid BGP peer, or would need to be injected by the attacker into the victim's BGP network on an existing, valid TCP connection to a BGP peer.

Weakness: CWE-400 (Uncontrolled Resource Consumption), CWE-399

## Which versions are affected by CVE-2019-16018?

It affects 1 product.


Products: Cisco Ios Xr.

## How do I fix CVE-2019-16018?

No fix has been published for CVE-2019-16018 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-16018 being exploited?

There is no known exploitation of CVE-2019-16018 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-2019-16018 and fix it if it is affected.

What it is: CVE-2019-16018 is a high-severity denial of service vulnerability in Cisco Ios Xr, published on 26 Jan 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2019-16018 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-2019-16018/ (Markdown: https://insights.sbomify.com/CVE-2019-16018/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-16018
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-16018
- OSV: https://osv.dev/vulnerability/CVE-2019-16018

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-16018/
Summaries are generated and may contain mistakes; the official description above is the record.