CVE-2026-62730 — Windows Wired AutoConfig Service Information Disclosure Vulnerability

Executive Summary

Buffer over-read in Windows Wired AutoConfig Service allows an authorized attacker to disclose information locally.

Overview

5.5

CVSS MEDIUM

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Information Disclosure

Weakness CWE-126: Buffer Over-read

Released Aug 11 2026

Last Updated Aug 11 2026

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.00387 — 0.31808 percentile

NVD CVSS 5.5 MEDIUM — matches MSRC

CVSS Vector

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

ATTACK VECTOR

Local

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

Low

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

High

INTEGRITY

None

AVAILABILITY

None

EXPLOIT CODE MATURITY

Unproven

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 4.8

EPSS Score

0.00387

probability of exploitation in the next 30 days

0.31808 percentile - updated 2026-08-14

View on FIRST.org

Affected Products

22 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1607 for 32-bit Systems	`5120418 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1607 for x64-based Systems	`5120418 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1809 for 32-bit Systems	`5120238 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1809 for x64-based Systems	`5120238 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 21H2 for 32-bit Systems	`5120249 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 21H2 for ARM64-based Systems	`5120249 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 21H2 for x64-based Systems	`5120249 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 22H2 for 32-bit Systems	`5120249 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 22H2 for ARM64-based Systems	`5120249 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 22H2 for x64-based Systems	`5120249 (Security Update)`	Important	Information Disclosure	Yes
Windows 11 Version 23H2 for ARM64-based Systems	`5120240 (Security Update)`	Important	Information Disclosure	Yes
Windows 11 Version 23H2 for x64-based Systems	`5120240 (Security Update)`	Important	Information Disclosure	Yes
Windows 11 Version 24H2 for ARM64-based Systems 5120994 (Security Hotpatch Update) 5121003 (Security Update) Important Information Disclosure 5101650 Base: 5.5 Temporal: 4.8 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C 10.0.26100.9106 10.0.26100.9168 Yes None Windows 11 Version 24H2 for x64-based Systems 5121003 (Security Update) 5120994 (Security Hotpatch Update) Important Information Disclosure 5101650 Base: 5.5 Temporal: 4.8 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C 10.0.26100.9168 10.0.26000.9106 Yes None Windows 11 Version 25H2 for ARM64-based Systems 5121003 (Security Update) 5120994 (Security Hotpatch Update) Important Information Disclosure 5101650 Base: 5.5 Temporal: 4.8 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C 10.0.26200.9168 10.0.26100.9106 Yes None Windows 11 Version 25H2 for x64-based Systems 5121003 (Security Update) 5120994 (Security Hotpatch Update) Important Information Disclosure 5101650 Base: 5.5 Temporal: 4.8 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C 10.0.26200.9168 10.0.26100.9106 Yes None Windows 11 Version 26H1 for ARM64-based Systems	`5121000 (Security Update)`	Important	Information Disclosure	Yes
Windows 11 version 26H1 for x64-based Systems	`5121000 (Security Update)`	Important	Information Disclosure	Yes
Windows Server 2012	`5120386 (Monthly Rollup)`	Important	Information Disclosure	Yes
Windows Server 2012 (Server Core installation)	`5120386 (Monthly Rollup)`	Important	Information Disclosure	Yes
Windows Server 2012 R2	`5120385 (Monthly Rollup)`	Important	Information Disclosure	Yes
Windows Server 2012 R2 (Server Core installation)	`5120385 (Monthly Rollup)`	Important	Information Disclosure	Yes
Windows Server 2016	`5120418 (Security Update)`	Important	Information Disclosure	Yes
Windows Server 2016 (Server Core installation)	`5120418 (Security Update)`	Important	Information Disclosure	Yes
Windows Server 2019	`5120238 (Security Update)`	Important	Information Disclosure	Yes
Windows Server 2019 (Server Core installation)	`5120238 (Security Update)`	Important	Information Disclosure	Yes

Patches

7 patches

Article	Type	Restart
`5120418`	Security Update	Yes
`5120238`	Security Update	Yes
`5120249`	Security Update	Yes
`5120240`	Security Update	Yes
`5121000`	Security Update	Yes
`5120386`	Monthly Rollup	Yes
`5120385`	Monthly Rollup	Yes

Patch Diff

ghidriff · dot3svc.dll (KB5121003)

Buffer over-read (CWE-126) in the Windows Wired AutoConfig service dot3svc.dll RpcUIResponse handler, local information disclosure of privileged-process heap memory. dot3svc.dll (802.1X wired authentication) exposes RpcUIResponse, which receives a UI response buffer from the client containing a _DOT3_UI_REQUEST structure and forwards it to Dot3AcmUIResponse. PRE: the handler took the embedded request pointer (*(param_3+8)) and used it without validating that the supplied buffer was at least the size of the structure, so a client-supplied buffer smaller than the _DOT3_UI_REQUEST record caused the service to read past the end of the buffer - a buffer over-read that discloses adjacent heap memory of the privileged (SYSTEM) service. Diff of dot3svc.dll 10.0.26100.8972 -> .9168 (Aug 11 2026, KB5121003) confirms the fix: the parameter is now a counted buffer (uint *param_3) and, gated behind CFR flag Feature_2872289593, RpcUIResponse validates the request pointer is non-null AND the buffer length (*param_3) is at least 0x28 (the structure size) before use - if (request == 0 || *param_3 < 0x28) return ERROR_INVALID_PARAMETER (0x57) - so an undersized buffer is rejected instead of over-read.

Pre-patch version 10.0.26100.8972 Download

Post-patch version 10.0.26100.9168 Download

Function	Address	Change	Note
`RpcUIResponse`	`code change`	code (buffer length validated before reading the request, CFR-gated)	Param changed to counted 'uint param_3'. Pre: passed (param_3+8) to Dot3AcmUIResponse with no size check. Post (Feature_2872289593): if (((longlong)(param_3+2) == 0) \|\| (*param_3 < 0x28)) return 0x57 (ERROR_INVALID_PARAMETER) before use - requires the buffer to hold the full 0x28-byte _DOT3_UI_REQUEST.
`Feature_2872289593`	`gate`	added (CFR gate)	CFR flag gating the buffer-length validation; the original unchecked read still ships when disabled.

View full diff report View RCA report

Attack Path

An undersized UI-response buffer makes the Wired AutoConfig service read past it, leaking heap memory

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

k0shl

References

MSRC Advisory MITRE NVD