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Fencer Vulns
medium 6.5

CVE-2026-34531 json

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

published 2026-03-31 7 mo ago modified 2026-10-26 13 d ago also GHSA-p44q-vqpr-4xmg , PYSEC-2026-2152 , EUVD-2026-18056

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 27%
public exploits
0
none known

Summary

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.

Patch / fix

  • pypi flask-httpauth 4.8.1
  • miguelgrinberg flask-httpauth 4.8.1
  • python-flask-httpauth Debian 14 4.8.1-1.1

debian advisories DEBIAN-CVE-2026-34531

  • python-Flask-HTTPAuth openSUSE Leap 16.0 4.8.0-bp160.2.1
  • python-Flask-HTTPAuth openSUSE Tumbleweed 4.8.1-1.1

opensuse advisories openSUSE-SU-2026:20576-1openSUSE-SU-2026:10518-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-34531 updated cvss 6.5

flask-httpauth: token verification callback invoked when missing or empty token was given by client

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
7 mo ago

Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
NVD 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
OSV 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N

Affected packages

ecosystem package affected fixed in
pypi flask-httpauth
<4.8.1
4.8.1

Affected products

  • miguelgrinberg Flask-HTTPAuth

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.