# CVE-2019-15998: Cisco IOS XR Software NETCONF Over Secure Shell ACL Bypass Vulnerability

> Attackers can bypass ACL restrictions to connect to NETCONF over SSH on Cisco IOS XR devices, requiring valid credentials for access.

- **Severity:** Medium 5.3 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 26 Nov 2019
- **Updated:** 19 Nov 2024
- **Also known as:** GHSA-w36j-549f-hchr

## What is CVE-2019-15998?

CVE-2019-15998 is a medium-severity missing authorization vulnerability in Cisco Ios Xr, published on 26 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the access-control logic of the NETCONF over Secure Shell (SSH) of Cisco IOS XR Software may allow connections despite an access control list (ACL) that is configured to deny access to the NETCONF over SSH of an affected device. The vulnerability is due to a missing check in the NETCONF over SSH access control list (ACL). An attacker could exploit this vulnerability by connecting to an affected device using NETCONF over SSH. A successful exploit could allow the attacker to connect to the device on the NETCONF port. Valid credentials are required to access the device. This vulnerability does not affect connections to the default SSH process on the device.

Weakness: CWE-862 (Missing Authorization), CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2019-15998?

It affects 1 product.


Products: Cisco Ios Xr.

## How do I fix CVE-2019-15998?

No fix has been published for CVE-2019-15998 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-15998 being exploited?

There is no known exploitation of CVE-2019-15998 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-2019-15998 and fix it if it is affected.

What it is: CVE-2019-15998 is a medium-severity missing authorization vulnerability in Cisco Ios Xr, published on 26 Nov 2019. 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-2019-15998 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-2019-15998/ (Markdown: https://insights.sbomify.com/CVE-2019-15998/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-15998
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-15998
- OSV: https://osv.dev/vulnerability/CVE-2019-15998

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From sbomify Insights: https://insights.sbomify.com/CVE-2019-15998/
Summaries are generated and may contain mistakes; the official description above is the record.