GHSA-4f9r-x588-pp2h
Fleet's user account creation via invite does not enforce invited email address
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
github.com/fleetdm/fleet/v4Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Fleet contained an issue in the user invitation flow where the email address provided during invite acceptance was not validated against the email address associated with the invite. An attacker who obtained a valid invite token could create an account under an arbitrary email address while inheriting the role granted by the invite, including global admin.
Impact
If an attacker gains access to a valid invite token, they can create a Fleet user account with an email address of their choosing while inheriting the invite’s assigned role and team memberships.
This issue:
- Requires possession of a valid invite token
- Does not bypass authentication controls beyond invite-based account creation
- Does not expose data without successful account creation
Workarounds
If upgrading immediately is not possible:
- Treat invite links as sensitive credentials and avoid sharing them in public or semi-public channels (e.g., Slack, Teams).
- Revoke and reissue invites if there is any concern that an invite link may have been exposed.
- Prefer issuing invites with the minimum required privileges and elevating roles after account creation when appropriate.
For more information
If there are any questions or comments about this advisory:
Send an email to [email protected]
Credits
Fleet thanks @fuzzztf for responsibly reporting this issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/fleetdm/fleet/v4 | all versions | 4.81.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/fleetdm/fleet/v4. 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 github.com/fleetdm/fleet/v4 to 4.81.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4f9r-x588-pp2h 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-4f9r-x588-pp2h 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-4f9r-x588-pp2h. 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-4f9r-x588-pp2h in your dependencies?
O3 detects GHSA-4f9r-x588-pp2h across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.