GHSA-qq2p-4282-cfc5 eduMFA: Incorrect InnoDB snapshot isolation possibly allows token reusage
Attackers can reuse one-time tokens in eduMFA due to database race conditions, bypassing authentication if specific database isolation settings are used.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is GHSA-qq2p-4282-cfc5?
GHSA-qq2p-4282-cfc5 is a vulnerability in edumfa, published on 18 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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/
Which versions are affected by GHSA-qq2p-4282-cfc5?
2 open source packages ship an affected version, including edumfa.
| Package | Affected | Fixed in |
|---|---|---|
edumfa PyPI | All versions | 2.9.1 |
edumfa PyPI | All versions | 2.9.1 |
How do I fix GHSA-qq2p-4282-cfc5?
Upgrade edumfa to 2.9.1 or later.
Is GHSA-qq2p-4282-cfc5 being exploited?
There is no known exploitation of GHSA-qq2p-4282-cfc5 in the wild and no public exploit code.