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CVE-2026-23518

Fleetdm Fleet vulnerability

9.8 CRITICALEPSS 0.26%
  1. Published21 Jan 2026

Description

Fleet is open source device management software. In versions prior to 4.78.3, 4.77.1, 4.76.2, 4.75.2, and 4.53.3, a vulnerability in Fleet's Windows MDM enrollment flow could allow an attacker to submit forged authentication tokens that are not properly validated. Because JWT signatures were not verified, Fleet could accept attacker-controlled identity claims, enabling enrollment of unauthorized devices under arbitrary Azure AD user identities. Versions 4.78.3, 4.77.1, 4.76.2, 4.75.2, and 4.53.3 fix the issue. If an immediate upgrade is not possible, affected Fleet users should temporarily disable Windows MDM.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Fleetdm Fleet≥ 4.75.0 < 4.75.2 · ≥ 4.76.0 < 4.76.2 · ≥ 4.78.0 < 4.78.3 · < 4.53.3

Remediation

Fixed in
Fleetdm Fleet≥ 4.75.2

References

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Frequently asked

Is CVE-2026-23518 being actively exploited?

CVE-2026-23518 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.26%.

How severe is CVE-2026-23518?

CVE-2026-23518 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.26% probability of exploitation.

Which products are affected by CVE-2026-23518?

Affected products include Fleetdm Fleet.

How do I fix CVE-2026-23518?

Upgrade affected software to a fixed version, for example Fleetdm Fleet 4.75.2 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-23518 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.