EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
@fastify/passport📦@fastify/passportReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
The CSRF protection enforced by the @fastify/csrf-protection library, when combined with @fastify/passport, can be bypassed by network and same-site attackers.
Details
fastify/csrf-protection implements the synchronizer token pattern (using plugins @fastify/session and @fastify/secure-session) by storing a random value used for CSRF token generation in the _csrf attribute of a user's session.
The @fastify/passport library does not clear the session object upon authentication, preserving the _csrf attribute between pre-login and authenticated sessions. Consequently, CSRF tokens generated before authentication are still valid. Network and same-site attackers can thus obtain a CSRF token for their pre-session, fixate that pre-session in the victim's browser via cookie tossing, and then perform a CSRF attack after the victim authenticates.
Fix
As a solution, newer versions of @fastify/passport include the configuration options
clearSessionOnLogin (default: true)andclearSessionIgnoreFields (default: ['session'])
to clear all the session attributes by default, preserving those explicitly defined in clearSessionIgnoreFields.
Credits
- Pedro Adão (@pedromigueladao), Instituto Superior Técnico, University of Lisbon
- Marco Squarcina (@lavish), Security & Privacy Research Unit, TU Wien
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @fastify/passport | all versions | 1.1.0 |
| 📦npm | @fastify/passport | ≥ 2.0.0&&< 2.3.0 | 2.3.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @fastify/passport. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @fastify/passport to 1.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2ccf-ffrj-m4qw is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-2ccf-ffrj-m4qw is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-2ccf-ffrj-m4qw. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-2ccf-ffrj-m4qw in your dependencies?
O3 detects GHSA-2ccf-ffrj-m4qw across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.