Summary
Fleet: Device lock PIN can be predicted if lock time is known
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.
Workarounds
There are no known workarounds for this issue. Customers should upgrade to a patched version.
For more information
If there are any questions or comments about this advisory:
Email Fleet at [email protected]
Join #fleet in osquery Slack
Credits
Fleet thanks @secfox-ai for responsibly reporting this issue.
Impact
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 multiple days.
- 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.
Security-sensitive operations rely on values that are predictable or insufficiently random. Typical impact: forged tokens, guessable identifiers, or broken cryptographic protocols.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-23999? CVE-2026-23999 is a medium-severity use of insufficiently random values vulnerability in github.com/fleetdm/fleet/v4 (go), affecting versions < 4.80.1. It is fixed in 4.80.1. Security-sensitive operations rely on values that are predictable or insufficiently random.
- Which versions of github.com/fleetdm/fleet/v4 are affected by CVE-2026-23999? github.com/fleetdm/fleet/v4 (go) versions < 4.80.1 is affected.
- Is there a fix for CVE-2026-23999? Yes. CVE-2026-23999 is fixed in 4.80.1. Upgrade to this version or later.
- Is CVE-2026-23999 exploitable, and should I be worried? Whether CVE-2026-23999 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-23999 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-23999? Upgrade
github.com/fleetdm/fleet/v4to 4.80.1 or later.