Firefly III has a MFA bypass in oauth flowGHSA-4gm4-c4mh-4p7w
MEDIUMGHSA-4gm4-c4mh-4p7w is a medium-severity (CVSS 5.9) Improper Authentication vulnerability in grumpydictator/firefly-iii. A fix is available for grumpydictator/firefly-iii — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-4gm4-c4mh-4p7w.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
grumpydictator/firefly-iiiReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Impact
A MFA bypass in the Firefly III OAuth flow may allow malicious users to bypass the MFA-check. This allows malicious users to use password spraying to gain access to your Firefly III data using passwords stolen from other sources. As OAuth applications are easily enumerable using an incrementing id, an attacker could try sign an OAuth application up to a users profile quite easily if they have created one. The attacker would also need to know the victims username and password.
Patches
Problem has been patched in Firefly III v6.1.17 and up.
Workarounds
- Use a unique password for your Firefly III instance,
- Store your password securely, i.e. in a password manager or in your head.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | grumpydictator/firefly-iii | all versions | 6.1.17composer require grumpydictator/firefly-iii:^6.1.17 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for grumpydictator/firefly-iii, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update grumpydictator/firefly-iii to 6.1.17 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4gm4-c4mh-4p7w is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is GHSA-4gm4-c4mh-4p7w in your dependencies?
Find it across Packagist, including transitive dependencies.