Flask-HTTPAuth invokes token verification callback when missing or empty token was given by client

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Summary

CVECVE-2026-34531
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-01 21:17:01 UTC
Updated2026-04-16 16:21:05 UTC
DescriptionFlask-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.

Risk And Classification

Primary CVSS: v3.1 8.2 HIGH from [email protected]

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

EPSS: 0.000500000 probability, percentile 0.153960000 (date 2026-04-21)

Problem Types: CWE-287 | NVD-CWE-noinfo | CWE-287 CWE-287: Improper Authentication

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary8.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
3.1CNADECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
High
Availability
None

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Miguelgrinberg Flask-httpauth All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Miguelgrinberg Flask-HTTPAuth affected < 4.8.1 Not specified

References

ReferenceSourceLinkTags
github.com/miguelgrinberg/flask-httpauth/commit/b15ffe9e50e110d7174ccd94... [email protected] github.com Patch
github.com/miguelgrinberg/Flask-HTTPAuth/security/advisories/GHSA-p44q-v... [email protected] github.com Mitigation, Vendor Advisory
github.com/miguelgrinberg/Flask-HTTPAuth/releases/tag/v4.8.1 [email protected] github.com Product, Release Notes
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