OnlyPatch
Applocker Filter Driver (applockerfltr.sys)

CVE-2026-25184 — Applocker Filter Driver (applockerfltr.sys) Elevation of Privilege Vulnerability

Important CVSS 7 EPSS 0.00183 🔬 Patch diffed 2026-04 archive

Executive Summary

Concurrent execution using shared resource with improper synchronization ('race condition') in Applocker Filter Driver (applockerfltr.sys) allows an authorized attacker to elevate privileges locally.

Overview

7
CVSS HIGH
Important
MS Severity
Not Exploited
MS Exploit Status
Less Likely
MS Exploit Likelihood
Category Elevation of Privilege
Weakness CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Released Apr 14 2026
Last Updated Apr 14 2026
Publicly Disclosed No
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.00183 — 0.08107 percentile
NVD CVSS 7 HIGH — matches MSRC

CVSS Vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
ATTACK VECTOR
Local
ATTACK COMPLEXITY
High
PRIVILEGES REQUIRED
Low
USER INTERACTION
None
SCOPE
Unchanged
CONFIDENTIALITY
High
INTEGRITY
High
AVAILABILITY
High
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 6.1

EPSS Score

0.00183
probability of exploitation in the next 30 days
0.08107 percentile - updated 2026-08-14
View on FIRST.org

Affected Products

11 affected products
Product KB Article Severity Impact Restart Required
Windows 11 Version 23H2 for ARM64-based Systems 5082052 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 23H2 for x64-based Systems 5082052 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 24H2 for ARM64-based Systems 5083769 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 24H2 for x64-based Systems 5083769 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 25H2 for ARM64-based Systems 5083769 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 25H2 for x64-based Systems 5083769 (Security Update) Important Elevation of Privilege Yes
Windows 11 Version 26H1 for ARM64-based Systems 5083768 (Security Update) Important Elevation of Privilege Yes
Windows 11 version 26H1 for x64-based Systems 5083768 (Security Update) Important Elevation of Privilege Yes
Windows Server 2022, 23H2 Edition (Server Core installation) 5082060 (Security Update) Important Elevation of Privilege Yes
Windows Server 2025 5082063 (Security Update) Important Elevation of Privilege Yes
Windows Server 2025 (Server Core installation) 5082063 (Security Update) Important Elevation of Privilege Yes

Patches

5 patches
Article Type Restart
5082052 Security Update Yes
5083769 Security Update Yes
5083768 Security Update Yes
5082060 Security Update Yes
5082063 Security Update Yes

Patch Diff

ghidriff · applockerfltr.sys (KB5083769)

TOCTOU race in SmRegisterUninstallStringWithSessionOrigin — linked-list insertion performed under shared lock upgraded to exclusive lock via Feature_423566650. Two concurrent callers could corrupt the doubly-linked list of uninstall string data, leading to use-after-free.

Pre-patch version 10.0.26100.7920 Download
Post-patch version 10.0.26100.8246 Download
Function Address Change Note
SmRegisterUninstallStringWithSessionOrigin 140009e98 code, length, called Shared lock → exclusive lock for linked-list write
View full diff report View RCA report Download PoC

Attack Path

Linked-list insertion performed under a shared lock - two concurrent inserts corrupt the list

Attack path for CVE-2026-25184 Linked-list insertion performed under a shared lock - two concurrent inserts corrupt the list 01 — ENTRY Standard user triggers uninstall-string registration SmRegisterUninstallStringWithSessionOrigin in applockerfltr.sys; reachable without elevation. 02 — CONTROLLED INPUT Attacker drives two registrations concurrently from separate threads Both enter the insertion path at the same time. 03 — PATH Each caller inserts into a doubly-linked list of uninstall string data The insertion is a multi-pointer write: it must update Flink and Blink on both the new node and its neighbours. 04 — MISSING CHECK The write is performed while holding only a SHARED lock A shared lock permits concurrent holders, so two inserters interleave their pointer updates. The patch upgrades the lock to exclusive for the write, gated behind Feature_423566650. 05 — PRIMITIVE Corrupted list linkage leading to use-after-free Nodes lost or double-linked; a later traversal or unlink operates on a node that has already been freed.

Derived from the patch delta: the checks added by the vendor identify which fields crossed a trust boundary unvalidated. Reachability and privilege are taken from the call chain in the RCA report.

Known Exploits

Acknowledgments

Souhail Hammou

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