# Flask-Security-Too WebAuthn reauthentication freshness bypass

Source: https://junglewise.ai/threats/flask-security-too-webauthn-reauthentication-freshness-bypass-1d81eff2  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-07. Updated: 2026-07-08  
License: CC BY 4.0 with a link back

Severity: medium · CVSS 6.3 · Published 2026-07-07

Flask-Security-Too is a library used to handle user authentication and security in Python web applications. A flaw in its WebAuthn implementation allows an attacker who is already logged into their own account to bypass 'freshness' checks on a victim's session. This means if an attacker gains temporary access to a victim's active session, they can perform sensitive actions like changing passwords or emails by using their own security key instead of the victim's.

Technologies: [Flask-Security-Too (PyPI)](https://junglewise.ai/threats/technologies/flask-security-too). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** Medium severity, with a CVSS score of 6.3, published 7 July 2026.

**Which products and versions are affected?** Flask-Security-Too (PyPI) >= 5.8.0, <= 5.8.1.

**Is there a fix for This vulnerability?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is This vulnerability attacked?** It is attacked over the network, in a software library.

**Am I affected?** Check whether you run Flask-Security-Too (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A vulnerability in `flask_security/webauthn.py` allows a reauthentication freshness bypass. The `webauthn_verify_response` function updates the session's freshness timestamp (`fs_paa`) upon receiving a valid WebAuthn assertion, but it fails to verify that the user associated with the provided credential matches the `current_user` of the session. An authenticated attacker can obtain a `wan_state` token from a victim's session and submit their own WebAuthn assertion to satisfy the freshness requirement. This allows the attacker to access endpoints protected by `@auth_required(within=...)`, such as password changes or MFA configuration, within the victim's session context. This issue persists in version 5.8.1 despite a similar fix being applied to the OAuth path.

## Affected products

- pallets-eco Flask-Security-Too >= 5.8.0, <= 5.8.1

## Timeline

- 2026-05-22: other: Related OAuth freshness bypass (GHSA-97r5-pg8x-p63p) published
- 2026-07-07: disclosed: Advisory published by GitHub

## References

- [https://api.github.com/users/tonghuaroot](https://api.github.com/users/tonghuaroot)
- [https://github.com/tonghuaroot](https://github.com/tonghuaroot)
- [https://api.github.com/users/tonghuaroot/gists%7B/gist_id%7D](https://api.github.com/users/tonghuaroot/gists%7B/gist_id%7D)
- [https://api.github.com/users/tonghuaroot/repos](https://api.github.com/users/tonghuaroot/repos)
- [https://avatars.githubusercontent.com/u/23011166?v=4](https://avatars.githubusercontent.com/u/23011166?v=4)
- [https://api.github.com/users/tonghuaroot/events%7B/privacy%7D](https://api.github.com/users/tonghuaroot/events%7B/privacy%7D)

## Related threats

- [Pallets-Eco Flask-Security-Too OAuth reauthentication freshness bypass](https://junglewise.ai/threats/cve-2026-46715-pallets-eco-flask-security-too-oauth-reauthentication-freshness)
- [Open redirect vulnerability in Flask-Security-Too](https://junglewise.ai/threats/cve-2023-49438-open-redirect-vulnerability-in-flask-security-too)
- [Open Redirect in Flask-Security-Too](https://junglewise.ai/threats/open-redirect-in-flask-security-too-42401b09)
- [Open Redirect in Flask-Security-Too](https://junglewise.ai/threats/cve-2021-32618-open-redirect-in-flask-security-too)
- [CSRF Vuln can expose user's QRcode](https://junglewise.ai/threats/csrf-vuln-can-expose-user-s-qrcode-5d832024)