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Windows CVE-2026-23518

CRITICAL
Improper Verification of Cryptographic Signature (CWE-347)
2026-01-21 security-advisories@github.com GHSA-63m5-974w-448v
Windows Azure Fleet Suse
9.8
CVSS 3.1 · GitHub Advisory
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Severity by source

GitHub Advisory PRIMARY
9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SUSE
CRITICAL
qualitative

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

3
Analysis Generated
Mar 12, 2026 - 21:54 vuln.today
Patch released
Feb 27, 2026 - 16:14 nvd
Patch available
CVE Published
Jan 21, 2026 - 22:15 nvd
CRITICAL 9.8

DescriptionGitHub Advisory

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.

AnalysisAI

Fleet device management software has a signature verification bypass that allows attackers to install malicious firmware on managed devices across the fleet.

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Craft forged JWT token with arbitrary Azure AD claims
Delivery
Submit token to Fleet Windows MDM enrollment endpoint
Exploit
Fleet accepts unverified signature
Execution
Enroll unauthorized device under spoofed identity
Impact
Gain device management access
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Vulnerability AssessmentAI

Exploitation Fleet Windows MDM enrollment flow must be accessible and enabled. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment CVSS 9.8 with patch available. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker exploits the signature verification bypass to push malicious firmware to all devices managed by Fleet, establishing persistent backdoors across the entire device fleet.
Remediation Update Fleet to the patched version for your branch. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours: Identify all affected systems running versions and apply vendor patches immediately. …

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Vendor StatusVendor

SUSE

Severity: Critical
Product Status
openSUSE Leap 15.6 Fixed
SUSE Linux Enterprise Module for Package Hub 15 SP5 Fixed
SUSE Linux Enterprise Module for Package Hub 15 SP6 Fixed
openSUSE Leap 15.5 Fixed

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CVE-2026-23518 vulnerability details – vuln.today
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