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

Status: published. Published: 2024-01-03. Updated: 2026-11-08.

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.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/peteroupc/CBOR/commit/b4117dbbb4cd5a4a963f9d0c9aa132f033e15b95
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: ADP: CVE) — https://github.com/peteroupc/CBOR/commit/b4117dbbb4cd5a4a963f9d0c9aa132f033e15b95
- fix: PeterO.Cbor (NuGet): OSV reports a fixed version 4.5.1. Check the advisory for supported release branches. (source: OSV GHSA-6r92-cgxc-r5fg) — https://github.com/advisories/GHSA-6r92-cgxc-r5fg

## Affected products and versions

-  /  (PeterO.Cbor): ≥ 4.0.0; < 4.5.1 (affected, semver 2.0.0). Source: CNA: VulnCheck
-  / PeterO.Cbor (PeterO.Cbor): 4.0.0 (affected, NuGet); 4.0.1 (affected, NuGet); 4.1.0 (affected, NuGet); 4.1.1 (affected, NuGet); 4.1.2 (affected, NuGet); 4.1.3 (affected, NuGet); 4.2.0 (affected, NuGet); 4.3.0 (affected, NuGet); 4.4.0 (affected, NuGet); 4.4.1 (affected, NuGet); 4.4.2 (affected, NuGet); 4.4.4 (affected, NuGet); 4.5.0 (affected, NuGet); Ecosystem version events: introduced 4.0.0; fixed 4.5.1. Source: OSV GHSA-6r92-cgxc-r5fg

## Severity and prioritization

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: ADP: CISA-ADP

- CISA KEV: No listing in collected sources

- EPSS: 1.06% as of 2026-11-08; percentile 64.81%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-407

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/peteroupc/CBOR/security/advisories/GHSA-6r92-cgxc-r5fg (CNA: VulnCheck; vendor-advisory)

- https://github.com/peteroupc/CBOR/commit/b4117dbbb4cd5a4a963f9d0c9aa132f033e15b95 (CNA: VulnCheck; patch)

- https://github.com/peteroupc/CBOR/compare/v4.5...v4.5.1 (CNA: VulnCheck; related)

- https://github.com/advisories/GHSA-6r92-cgxc-r5fg (CNA: VulnCheck; vendor-advisory)

- https://vulncheck.com/advisories/vc-advisory-GHSA-6r92-cgxc-r5fg (CNA: VulnCheck; third-party-advisory)

- https://github.com/peteroupc/CBOR/security/advisories/GHSA-6r92-cgxc-r5fg (ADP: CVE; vendor-advisory, x_transferred)

- https://github.com/peteroupc/CBOR/commit/b4117dbbb4cd5a4a963f9d0c9aa132f033e15b95 (ADP: CVE; patch, x_transferred)

- https://github.com/peteroupc/CBOR/compare/v4.5...v4.5.1 (ADP: CVE; related, x_transferred)

- https://github.com/advisories/GHSA-6r92-cgxc-r5fg (ADP: CVE; third-party-advisory, x_transferred)

- https://vulncheck.com/advisories/vc-advisory-GHSA-6r92-cgxc-r5fg (ADP: CVE; third-party-advisory, x_transferred)

- https://github.com/advisories/GHSA-6r92-cgxc-r5fg (OSV / GitHub Security Advisories; advisory)

- https://osv.dev/vulnerability/GHSA-6r92-cgxc-r5fg (OSV / GitHub Security Advisories; osv)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2024-21909; retrieved 2026-11-08; source updated 2026-11-08

- OSV / GitHub Security Advisories: https://osv.dev/vulnerability/GHSA-6r92-cgxc-r5fg; retrieved 2026-11-08; source updated 2026-07-08

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2024-21909; retrieved 2026-11-08; source updated Not reported

Revision: 257ef08193403e0e24c29efb52e419131f342f2f83a293117b1113c47be99883

Canonical: https://y2.dev/cve/CVE-2024-21909

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