eduMFA: Incorrect InnoDB snapshot isolation possibly allows token reusage

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Description

Impact

For deployments using MySQL or MariaDB < 11.6.2 (or newer with innodb_snapshot_isolation=off) reusage of token values might be possible due to faulty transaction isolation inside the database. Exploiting this requires racing this transaction.
Affected are all tokentypes whose values are only supposed to be used once, for example TOTP, HOTP and likely also WebAuthN.

Affected Combinations:

  • MySQL (any version)
  • MariaDB with innodb_snapshot_isolation=OFF
  • innodb_snapshot_isolation was introduced in: MariaDB 10.6.18, MariaDB 10.11.8, MariaDB 11.0.6, MariaDB 11.1.5, MariaDB 11.2.4, MariaDB 11.4.2
    with default OFF, can be turned ON as a workaround
  • for MariaDB >= 11.6.2 the default is ON, which is not affected
  • Same rules applies for Galera with underlying MariaDB

Patches

Fixed in version 2.9.1 by locking rows prior to write with SELECT FOR UPDATE.

Workarounds

Set innodb_snapshot_isolation to ON (default in MariaDB >= 11.6.2, e.g packaged in Debian 13).

Resources

https://mariadb.com/resources/blog/isolation-level-violation-testing-and-debugging-in-mariadb/

Basic information

Type
reviewed
Severity
high
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2026-05-18 15:36:18 UTC
Updated
2026-05-18 15:36:19 UTC
GitHub reviewed
2026-05-18 15:36:18 UTC

CVSS Scores

Base score Version Severity Vector
7.1 4.0 —
CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:H/VI:L/VA:L/SC:H/SI:L/SA:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:H)
Exploitation depends on constrained or hard-to-reproduce conditions.
Attack requirements (AT:P)
Additional preconditions must be present for exploitation.
Privileges required (PR:L)
Low privileges are required.
User interaction (UI:P)
A user has to participate (for example click/open/approve).
Vulnerable system confidentiality impact (VC:H)
High confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:L)
Limited integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:L)
Limited availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:H)
High confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:L)
Limited integrity impact on subsequent systems.
Subsequent system availability impact (SA:L)
Limited availability impact on subsequent systems.

Identifiers

Type Value
GHSA GHSA-qq2p-4282-cfc5 ↗

CWEs

CWE id Name
CWE-285 Improper Authorization

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
pip edumfa < 2.9.1 2.9.1 —

References

cvelogic Threat Intelligence