CVE-2026-23999
Fleet: Device lock PIN can be predicted if lock time is known
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
Fleet is open source device management software. In versions prior to 4.80.1, Fleet generated device lock and wipe PINs using a predictable algorithm based solely on the current Unix timestamp. Because no secret key or additional entropy was used, the resulting PIN could potentially be derived if the approximate time the device was locked is known. Fleet’s device lock and wipe commands generate a 6-digit PIN that is displayed to administrators for unlocking a device. In affected versions, this PIN was deterministically derived from the current timestamp. An attacker with physical possession of a locked device and knowledge of the approximate time the lock command was issued could theoretically predict the correct PIN within a limited search window. However, successful exploitation is constrained by multiple factors: Physical access to the device is required, the approximate lock time must be known, the operating system enforces rate limiting on PIN entry attempts, attempts would need to be spread over, and device wipe operations would typically complete before sufficient attempts could be made. As a result, this issue does not allow remote exploitation, fleet-wide compromise, or bypass of Fleet authentication controls. Version 4.80.1 contains a patch. No known workarounds are available.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/fleetdm/fleet/v4 | all versions | 4.80.1 |
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 4.80.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-23999 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 CVE-2026-23999 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 CVE-2026-23999. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-23999 in your dependencies?
O3 detects CVE-2026-23999 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.