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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-34531: 0.34% estimated exploitation activity in the next 30 days; percentile 27.18 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary 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. Notes - This issue applies only to token authentication - This issue applies only when the application verifies tokens by searching for them in a user database. - This issue applies only if the application stores empty strings as user tokens when the user does not have an assigned token. It does not apply if the application sets those tokens to NULL instead. - Tokens that are verified through cryptographic means (such as JWTs) are not affected by this issue. - Basic and Digest authentication are not affected by this issue. Remediation To protect…

Published by the source

31 Mar 2026, 23:48 UTC

Last modified by the source

13 Jul 2026, 07:26 UTC

Source last checked

26 Oct 2026, 13:41 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-p44q-vqpr-4xmg

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-p44q-vqpr-4xmg

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# Patch Next advisory brief: CVE-2026-34531

Advisory: Flask-HTTPAuth invokes token verification callback when missing or empty token was given by client
IDs: CVE-2026-34531, GHSA-p44q-vqpr-4xmg
Record: https://patchnext.com/advisories/cve-2026-34531 (revision 2, source checked 26 Oct 2026, 13:41 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: flask-httpauth 4.8.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI flask-httpauth: affected <= 4.8.0; fixed in 4.8.1

## Suggested inspection (read-only)
- `python -m pip show flask-httpauth`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on flask-httpauth.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-p44q-vqpr-4xmg (OSV record GHSA-p44q-vqpr-4xmg lists affected ranges: PyPI flask-httpauth >=0 <4.8.1 (fixed))
- Verified: https://github.com/advisories/GHSA-p44q-vqpr-4xmg (GitHub-reviewed advisory GHSA-p44q-vqpr-4xmg lists affected ranges: PyPI flask-httpauth >=0 <=4.8.0)

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