# CVE-2024-21909: Denial of service in CBOR library

> An attacker can cause a denial of service in applications using the PeterO.Cbor library by providing crafted data to decoding functions.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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:** Yes
- **Published:** 3 Jan 2024
- **Updated:** 14 Jul 2026
- **Also known as:** GHSA-6r92-cgxc-r5fg

## What is CVE-2024-21909?

CVE-2024-21909 is a high-severity denial of service vulnerability in peteroupc:cbor, published on 3 Jan 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

PeterO.Cbor versions 4.0.0 through 4.5.0 are vulnerable to a denial of 
service vulnerability. An attacker may trigger the denial of service 
condition by providing crafted data to the DecodeFromBytes or other 
decoding mechanisms in PeterO.Cbor. Depending on the usage of the 
library, an unauthenticated and remote attacker may be able to cause the
 denial of service condition.

Weakness: CWE-407 (Inefficient Algorithmic Complexity)

## Which versions are affected by CVE-2024-21909?

2 open source packages ship an affected version, including PeterO.Cbor. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `PeterO.Cbor` | NuGet | From 4.0.0 | 4.5.1 |
| `PeterO.Cbor` | NuGet | From 4.0.0 | 4.5.1 |

Products: Peteroupc Cbor.

## How do I fix CVE-2024-21909?

Upgrade PeterO.Cbor to 4.5.1 or later.

## Is CVE-2024-21909 being exploited?

There is no known exploitation of CVE-2024-21909 in the wild and no public exploit code.

## Other vulnerabilities in peteroupc:cbor

- [CVE-2024-23684](https://insights.sbomify.com/CVE-2024-23684/): upokecenter CBOR Denial of Service (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-21909 and fix it if it is affected.

What it is: CVE-2024-21909 is a high-severity denial of service vulnerability in peteroupc:cbor, published on 3 Jan 2024. 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-2024-21909 in the wild and no public exploit code.

Affected packages and fixed versions:
- PeterO.Cbor (NuGet): affected from 4.0.0; fixed in 4.5.1
- PeterO.Cbor (NuGet): affected from 4.0.0; fixed in 4.5.1

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-2024-21909/ (Markdown: https://insights.sbomify.com/CVE-2024-21909/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-21909
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-21909
- OSV: https://osv.dev/vulnerability/CVE-2024-21909

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-21909/
Summaries are generated and may contain mistakes; the official description above is the record.