CVE-2026-50491 — Code Integrity DLL (ci.dll) Elevation of Privilege Vulnerability

Executive Summary

Out-of-bounds read in Code Integrity DLL (ci.dll) allows an authorized attacker to elevate privileges locally.

Overview

7.8

CVSS HIGH

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Elevation of Privilege

Weakness CWE-125: Out-of-bounds Read

Released Jul 14 2026

Last Updated Jul 14 2026

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.0026 — 0.1771 percentile

NVD CVSS 7.8 HIGH — differs from 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: 6.1

EPSS Score

0.0026

probability of exploitation in the next 30 days

0.1771 percentile - updated 2026-08-14

View on FIRST.org

Affected Products

27 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1607 for 32-bit Systems	`5099535 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1607 for x64-based Systems	`5099535 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1809 for 32-bit Systems	`5099538 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1809 for x64-based Systems	`5099538 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 21H2 for 32-bit Systems	`5099539 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 21H2 for ARM64-based Systems	`5099539 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 21H2 for x64-based Systems	`5099539 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 22H2 for 32-bit Systems	`5099539 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 22H2 for ARM64-based Systems	`5099539 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 22H2 for x64-based Systems	`5099539 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 24H2 for ARM64-based Systems	`5101650 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 24H2 for x64-based Systems	`5101650 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 25H2 for ARM64-based Systems	`5101650 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 25H2 for x64-based Systems	`5101650 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 26H1 for ARM64-based Systems	`5101649 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 version 26H1 for x64-based Systems	`5101649 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2012	`5099445 (Monthly Rollup)`	Important	Elevation of Privilege	Yes
Windows Server 2012 (Server Core installation)	`5099445 (Monthly Rollup)`	Important	Elevation of Privilege	Yes
Windows Server 2012 R2	`5099444 (Monthly Rollup)`	Important	Elevation of Privilege	Yes
Windows Server 2012 R2 (Server Core installation)	`5099444 (Monthly Rollup)`	Important	Elevation of Privilege	Yes
Windows Server 2016	`5099535 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2016 (Server Core installation)	`5099535 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2019	`5099538 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2019 (Server Core installation)	`5099538 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2022	`5099540 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2025	`5099536 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2025 (Server Core installation)	`5099536 (Security Update)`	Important	Elevation of Privilege	Yes

Patches

9 patches

Article	Type	Restart
`5099535`	Security Update	Yes
`5099538`	Security Update	Yes
`5099539`	Security Update	Yes
`5101650`	Security Update	Yes
`5101649`	Security Update	Yes
`5099445`	Monthly Rollup	Yes
`5099444`	Monthly Rollup	Yes
`5099540`	Security Update	Yes
`5099536`	Security Update	Yes

Patch Diff

ghidriff · ci.dll (KB5101650)

Out-of-bounds read (CWE-125) with type confusion (CWE-843) in the Windows Code Integrity driver ci.dll SIPolicy version-block parser, local EoP to SYSTEM. To match Windows Defender Application Control (WDAC / System Integrity) policy rules that key on an image's file version and OriginalFilename, ci.dll parses the image's VS_VERSIONINFO resource via SIPolicyGetOriginalFilenameAndVersionFromImageBase -> SIPolicyGetVersionInfo / SIPolicyCheckVerBlock / SIPolicyQuerySubVerBlock / SIPolicyQueryVersionFields, walking the nested block tree (VS_FIXEDFILEINFO, StringFileInfo/VarFileInfo/Translation). PRE: these parsers trusted each block's declared wLength / value length / node type without validating them against the parent block bounds or verifying the VS_FIXEDFILEINFO signature, so a crafted version resource yields (a) an out-of-bounds read when a child block's length/offset runs past the parent block (CWE-125), and (b) type confusion when a node is consumed as VS_FIXEDFILEINFO / the wrong record type without the 0xFEEF04BD signature check (CWE-843). Because code-integrity/WDAC evaluation runs in kernel context, and exploitation requires winning a race (AC:H), the malformed-parse is an EoP-to-SYSTEM primitive. Diff of ci.dll 10.0.26100.8737 -> .8875 (Jul 14 2026, KB5101650) confirms the fix: gated behind CFR flags Feature_1311764795 / Feature_2390291770, the version-block parsers add bounds and structure validation at each descent - SIPolicyGetVersionInfo now requires the block to be >=0x5b bytes with the declared length within the available size and checks the VS_FIXEDFILEINFO signature (*(int*)(base+0x14) == 0xFEEF04BD); SIPolicyCheckVerBlock/QuerySubVerBlock validate each sub-block's aligned length+offset against the parent size and enforce even alignment before reading.

Pre-patch version 10.0.26100.8737 Download

Post-patch version 10.0.26100.8875 Download

Function	Address	Change	Note
`SIPolicyGetVersionInfo`	`code change`	code (VS_FIXEDFILEINFO signature + length validation added, CFR-gated)	Post adds: require (0x5b < param_2) && (0x5b < param_1) && (param_1 <= param_2) && ((int)(param_1+0x14) == 0xFEEF04BD) before reading the fixed-file-info fields, so an undersized/misaligned or non-VS_FIXEDFILEINFO block is rejected (blocks OOB read + type confusion).
`SIPolicyCheckVerBlock`	`code change`	code (sub-block length/offset bounded against parent)	Post: requires 7 < param_2, 7 < uVar1 <= param_2, validates the string length via RtlStringCbLengthW, and checks aligned(length)+child-offset <= parent length and param_2 >= that computed size before descending.
`SIPolicyQuerySubVerBlock`	`code change`	code (alignment + bounds checks on the block walk)	Post adds even-alignment ((param_1 & 1)==0), range ((ushort)(param_1-8) < 0x7ff9), value-length bound (uVar4 <= uVar1*2) and pointer bound (puVar13 <= param_1) while walking the block tree.
`SIPolicyQueryVersionFields`	`code change`	code (length validation on extracted fields)	Post adds signed-length checks and a <0xffff length bound plus RtlStringCbLengthW validation on the extracted version strings.
`Feature_1311764795 / Feature_2390291770`	`gate`	added (CFR gate)	CFR flags gating the hardened version-block validation; the original under-validating parser still ships when disabled.

View full diff report View RCA report

Attack Path

A crafted image version resource is walked by the kernel Code Integrity policy parser without bounds/type checks, causing OOB read and type confusion

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

grass341
Souhail Hammou

References

MSRC Advisory MITRE NVD