CVE-2026-48574 — Windows Media Remote Code Execution Vulnerability

Executive Summary

Heap-based buffer overflow in Windows Media allows an unauthorized attacker to execute code locally.

Overview

7.8

CVSS HIGH

Critical

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Remote Code Execution

Weakness CWE-122: Heap-based Buffer Overflow

Released Jun 9 2026

Last Updated Jun 9 2026

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.00445 — 0.36906 percentile

NVD CVSS 7.8 HIGH — matches MSRC

CVSS Vector

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

ATTACK VECTOR

Local

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

None

USER INTERACTION

Required

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

0.00445

probability of exploitation in the next 30 days

0.36906 percentile - updated 2026-08-14

View on FIRST.org

Affected Products

30 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1607 for 32-bit Systems	`5094122 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1607 for x64-based Systems	`5094122 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1809 for 32-bit Systems	`5094123 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1809 for x64-based Systems	`5094123 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H2 for 32-bit Systems	`5094127 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H2 for ARM64-based Systems	`5094127 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H2 for x64-based Systems	`5094127 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 22H2 for 32-bit Systems	`5094127 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 22H2 for ARM64-based Systems	`5094127 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 22H2 for x64-based Systems	`5094127 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 23H2 for ARM64-based Systems	`5093998 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 23H2 for x64-based Systems	`5093998 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 24H2 for ARM64-based Systems	`5094126 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 24H2 for x64-based Systems	`5094126 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 25H2 for ARM64-based Systems	`5094126 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 25H2 for x64-based Systems	`5094126 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 26H1 for ARM64-based Systems	`5095051 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 version 26H1 for x64-based Systems	`5095051 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2012	`5094042 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2012 (Server Core installation)	`5094042 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2012 R2	`5094041 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2012 R2 (Server Core installation)	`5094041 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2016	`5094122 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2016 (Server Core installation)	`5094122 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2019	`5094123 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2019 (Server Core installation)	`5094123 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2022	`5094128 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2022 (Server Core installation)	`5094128 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2025	`5094125 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2025 (Server Core installation)	`5094125 (Security Update)`	Critical	Remote Code Execution	Yes

Patches

10 patches

Article	Type	Restart
`5094122`	Security Update	Yes
`5094123`	Security Update	Yes
`5094127`	Security Update	Yes
`5093998`	Security Update	Yes
`5094126`	Security Update	Yes
`5095051`	Security Update	Yes
`5094042`	Monthly Rollup	Yes
`5094041`	Monthly Rollup	Yes
`5094128`	Security Update	Yes
`5094125`	Security Update	Yes

Patch Diff

ghidriff · mfmkvsrcsnk.dll (KB5094126)

Heap buffer overflow (CWE-122) via a store-before-bounds-check in the Windows Media Foundation MKV source mfmkvsrcsnk.dll MkvMfStreamVideoHEVC::GetMFMediaType, Critical RCE on opening a crafted HEVC media file (UI:R). Parsing the HEVC track CodecPrivate (hvcC), the function records each parameter-set NAL length in a table at this+0x1E0 that is 0x800 bytes = 512 DWORD entries (valid index 0-511). PRE: it wrote *(this+0x1e0 + v3*4) = nalUnitLength+4 FIRST, then incremented v3 and only afterward checked v3 > 0x200. When the index reaches 512 (already out of range) it executes table[512]=len+4, a 4-byte write immediately past the 0x800-byte table, before the check stops parsing. The written value is nalUnitLength+4 big-endian (4..0x10003), attacker-influenced; the NAL type is checked once per array (not per NAL), so a single parameter-set array with numNalus=513 gives 513 store targets and ~1KB CodecPrivate drives the index to 512. Diff of mfmkvsrcsnk.dll 10.0.26100.8328 -> .8655 (Jun 9 2026, KB5094126) confirms the fix: the bound is now checked before the write and the store is guarded by (index < 0x200), so the out-of-bounds table[512] write no longer occurs. Unconditional fix (no CFR flag).

Pre-patch version 10.0.26100.8328 Download

Post-patch version 10.0.26100.8655 Download

Function	Address	Change	Note
`MkvMfSourceLib::MkvMfStreamVideoHEVC::GetMFMediaType`	`code change`	code (bounds check moved before the table store)	Pre: (this+0x1e0 + v34) = nalUnitLength+4; v3++; if (0x200 < v3) fail -> table[512] written once before the check. Post: bound (0x200 < idx) checked up front and the store guarded by (idx < 0x200), eliminating the OOB write at index 512. Table at this+0x1E0 is 0x800 bytes / 512 DWORD entries.

View full diff report View RCA report

Attack Path

HEVC CodecPrivate with numNalus=513 makes the length table store one 4-byte entry past its 512-slot end before the check fires

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

No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.

Acknowledgments

cyanbamboo and b2ahex
Anonymous
Kyeongmin Kim (@hareh4ru)

References

MSRC Advisory MITRE NVD