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CVE-2026-23518

CRITICALCVSS 9.3/10EPSS 0.23%

Last modified

CVE-2026-23518 is a critical-severity vulnerability rated 9.3/10 on the CVSS scale. 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. EPSS estimates a 0.23% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS 4.0
9.3/10

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability
0.23%

13.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
FleetdmFleet< 4.53.3
FleetdmFleet>= 4.75.0, < 4.75.2
FleetdmFleet>= 4.76.0, < 4.76.2
FleetdmFleet>= 4.78.0, < 4.78.3
FleetdmFleet4.77.0

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-23518?
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.
How severe is CVE-2026-23518?
CVE-2026-23518 has a CVSS score of 9.3/10 (CRITICAL severity). The EPSS model estimates a 0.23% probability of exploitation in the next 30 days.
How do I fix CVE-2026-23518?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-23518?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST