# CVE-2024-20312: Null dereference in Cisco IOS XE Software

> An adjacent attacker can cause a denial of service on Cisco IOS devices by sending crafted IS-IS packets after forming an adjacency.

- **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:** 27 Mar 2024
- **Updated:** 26 Aug 2025
- **Also known as:** GHSA-h59x-f52x-4wxj

## What is CVE-2024-20312?

CVE-2024-20312 is a high-severity vulnerability in Cisco Ios, published on 27 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 Intermediate System-to-Intermediate System (IS-IS) protocol of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on an affected device.

 This vulnerability is due to insufficient input validation when parsing an ingress IS-IS packet. An attacker could exploit this vulnerability by sending a crafted IS-IS packet to an affected device after forming an adjacency. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition.

 Note: The IS-IS protocol is a routing protocol. To exploit this vulnerability, an attacker must be Layer 2-adjacent to the affected device and have formed an adjacency.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2024-20312?

It affects 2 products.


Products: Cisco Ios, Cisco Ios Xe.

## How do I fix CVE-2024-20312?

No fix has been published for CVE-2024-20312 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-20312 being exploited?

There is no known exploitation of CVE-2024-20312 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Ios

- [CVE-2017-12240](https://insights.sbomify.com/CVE-2017-12240/): Cisco IOS and IOS XE Software DHCP Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2017-3881](https://insights.sbomify.com/CVE-2017-3881/): Cisco IOS and IOS XE Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2018-0167](https://insights.sbomify.com/CVE-2018-0167/): Cisco IOS, XR, and XE Software Buffer Overflow (high 8.8, exploited in the wild)
- [CVE-2017-6736](https://insights.sbomify.com/CVE-2017-6736/): Cisco IOS and IOS XE Software SNMP Remote Code Execution (high 8.8, exploited in the wild)
- [CVE-2017-6737](https://insights.sbomify.com/CVE-2017-6737/): Cisco IOS and IOS XE Software SNMP Remote Code Execution (high 8.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-20312 and fix it if it is affected.

What it is: CVE-2024-20312 is a high-severity vulnerability in Cisco Ios, published on 27 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-2024-20312 in the wild and no public exploit code.

Affected product: Cisco Ios. 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-2024-20312/ (Markdown: https://insights.sbomify.com/CVE-2024-20312/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-20312
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-20312
- OSV: https://osv.dev/vulnerability/CVE-2024-20312

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-20312/
Summaries are generated and may contain mistakes; the official description above is the record.