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Vulnerability record · CVE-2026-34531 · published 1 April 2026

CVE-2026-34531: Miguelgrinberg flask-httpauth improper authentication vulnerability

Miguelgrinberg · Flask Httpauth

Flask-HTTPAuth provides Basic, Digest and Token HTTP authentication for Flask routes. Prior to version 4.8.1, in a situation where the client makes a request to a token protected resource without passing a token, or passing an empty token, Flask-HTTPAuth would invoke the application's token verification callback function with the token argument set to an empty string. If the application had any users in its database with an empty string set as their token, then it could potentially authenticate the client request against any of those users. This issue has been patched in version 4.8.1.

8.2 CVSS 3.1 High EPSS 0.48% · top 61.2% CWE-287 · Improper authentication
8.2CVSS 3.1 base score
0.48%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

Description

Flask-HTTPAuth provides Basic, Digest and Token HTTP authentication for Flask routes. Prior to version 4.8.1, in a situation where the client makes a request to a token protected resource without passing a token, or passing an empty token, Flask-HTTPAuth would invoke the application's token verification callback function with the token argument set to an empty string. If the application had any users in its database with an empty string set as their token, then it could potentially authenticate the client request against any of those users. This issue has been patched in version 4.8.1.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/miguelgrinberg/Flask-HTTPAuth/releases/tag/v4.8.1 ProductRelease Notes
https://github.com/miguelgrinberg/Flask-HTTPAuth/security/advisories/GHSA-p44q-vqpr-4xmg MitigationVendor Advisory
https://github.com/miguelgrinberg/flask-httpauth/commit/b15ffe9e50e110d7174ccd944f642079e1dcf9ee Patch
https://lists.debian.org/debian-lts-announce/2026/05/msg00049.html

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Source: NIST National Vulnerability Database (record CVE-2026-34531), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.