CVE-2025-55692 — Windows Error Reporting Service Elevation of Privilege Vulnerability

Executive Summary

Improper input validation in Windows Error Reporting allows an authorized attacker to elevate privileges locally.

Overview

7.8

CVSS HIGH

Important

MS Severity

Not Exploited

MS Exploit Status

More Likely

MS Exploit Likelihood

Category Elevation of Privilege

Weakness CWE-20: Improper Input Validation

Released Oct 14 2025

Last Updated Oct 14 2025

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.03158 — 0.86834 percentile

NVD CVSS 7.8 HIGH — matches MSRC

CVSS Vector

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

ATTACK VECTOR

Local

ATTACK COMPLEXITY

Low

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: 6.8

EPSS Score

0.03158

probability of exploitation in the next 30 days

0.86834 percentile - updated 2026-08-14

View on FIRST.org

Affected Products

31 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 for 32-bit Systems	`5066837 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 for x64-based Systems	`5066837 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1607 for 32-bit Systems	`5066836 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1607 for x64-based Systems	`5066836 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1809 for 32-bit Systems	`5066586 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1809 for x64-based Systems	`5066586 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 21H2 for 32-bit Systems	`5066791 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 21H2 for ARM64-based Systems	`5066791 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 21H2 for x64-based Systems	`5066791 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 22H2 for 32-bit Systems	`5066791 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 22H2 for ARM64-based Systems	`5066791 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 22H2 for x64-based Systems	`5066791 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 22H2 for ARM64-based Systems	`5066793 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 22H2 for x64-based Systems	`5066793 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 23H2 for ARM64-based Systems	`5066793 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 23H2 for x64-based Systems	`5066793 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 24H2 for ARM64-based Systems	`5066835 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 24H2 for x64-based Systems	`5066835 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 25H2 for ARM64-based Systems	`5066835 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 25H2 for x64-based Systems	`5066835 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2012 R2	`5066873 (Monthly Rollup)`	Important	Elevation of Privilege	Yes
Windows Server 2012 R2 (Server Core installation)	`5066873 (Monthly Rollup)`	Important	Elevation of Privilege	Yes
Windows Server 2016	`5066836 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2016 (Server Core installation)	`5066836 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2019	`5066586 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2019 (Server Core installation)	`5066586 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2022	`5066782 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2022 (Server Core installation)	`5066782 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2022, 23H2 Edition (Server Core installation)	`5066780 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2025	`5066835 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2025 (Server Core installation)	`5066835 (Security Update)`	Important	Elevation of Privilege	Yes

Patches

9 patches

Article	Type	Restart
`5066837`	Security Update	Yes
`5066836`	Security Update	Yes
`5066586`	Security Update	Yes
`5066791`	Security Update	Yes
`5066793`	Security Update	Yes
`5066835`	Security Update	Yes
`5066873`	Monthly Rollup	Yes
`5066782`	Security Update	Yes
`5066780`	Security Update	Yes

Patch Diff

ghidriff · wersvc.dll (KB5066835)

Improper input validation (CWE-20) in the Windows Error Reporting Service wersvc.dll, local elevation of privilege to administrator (Important, AV:L, AC:L, CVSS 7.8, Exploitation More Likely). Pre-patch, a WER service operation performed improper input validation on caller-supplied data, which a low-privileged local caller could abuse to elevate. This CVE was fixed in the SAME October wersvc.dll servicing change as CVE-2025-55694 (CWE-284 access control), gated behind the single CFR flag Feature_1201448248. Across the whole October WER binary set (wermgr.exe, faultrep.dll, werfault.exe, werfaultsecure.exe - all self-diffed 0-delta rebuilds) only wersvc.dll changed, and its only code artifact is a capability/permission-bit helper (documented under CVE-2025-55694). A distinct input-validation routine for this CVE is NOT separately identifiable in the binary - the two fixes are consolidated under one flag. Recorded honestly at that level: the diff (wersvc.dll 10.0.26100.5074 -> .6899, KB5066835) is the shared, feature-gated WER hardening; no independent 55692-specific code patch is isolable.

Pre-patch version 10.0.26100.5074 Download

Post-patch version 10.0.26100.6899 Download

Function	Address	Change	Note
`wersvc October servicing change (shared with CVE-2025-55694)`	`code change`	code (consolidated feature-gated WER hardening, CFR-gated)	The input-validation tightening for this CVE ships within the same Feature_1201448248-gated wersvc.dll change as the access-control fix; the binary diff does not expose a separate, independently-isolable validation function. Only wersvc.dll changed in the October WER update (other WER binaries are 0-delta rebuilds).
`Feature_1201448248`	`gate`	added (CFR gate)	New October CFR flag consolidating the WER access-control (CVE-2025-55694) and input-validation (CVE-2025-55692) hardening; the pre-patch behaviour still ships when disabled.

View full diff report View RCA report

Attack Path

A low-privileged caller supplies improperly-validated input to a WER operation, elevating privilege

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.

Exploits & PoC

No public exploit or PoC has been linked for this CVE yet. When available, references are sourced from public repositories and may be unverified or non-functional — review carefully before use.

Detection Rules

No public Sigma or Nuclei detection rule has been mapped to this CVE yet. Coverage is concentrated on exploited / high-profile vulnerabilities; check SigmaHQ for updates.

Acknowledgments

Denis Faiustov with GMO Cybersecurity by Ierae
Ruslan Sayfiev with GMO Cybersecurity by Ierae

References

MSRC Advisory MITRE NVD