CVE-2026-33824 — Windows Internet Key Exchange (IKE) Service Extensions Remote Code Execution Vulnerability

Executive Summary

Double free in Windows IKE Extension allows an unauthorized attacker to execute code over a network.

Overview

9.8

CVSS CRITICAL

Critical

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Remote Code Execution

Weakness CWE-415: Double Free

Released Apr 14 2026

Last Updated Apr 14 2026

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.5585 — 0.98954 percentile

NVD CVSS 9.8 CRITICAL — matches MSRC

CVSS Vector

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

ATTACK VECTOR

Network

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

None

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

High

INTEGRITY

High

AVAILABILITY

High

EXPLOIT CODE MATURITY

Unproven

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 8.5

EPSS Score

0.5585

probability of exploitation in the next 30 days

0.98954 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	`5082198 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1607 for x64-based Systems	`5082198 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1809 for 32-bit Systems	`5082123 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1809 for x64-based Systems	`5082123 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H2 for 32-bit Systems	`5082200 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H2 for ARM64-based Systems	`5082200 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H2 for x64-based Systems	`5082200 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 22H2 for 32-bit Systems	`5082200 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 22H2 for ARM64-based Systems	`5082200 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 22H2 for x64-based Systems	`5082200 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 23H2 for ARM64-based Systems	`5082052 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 23H2 for x64-based Systems	`5082052 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 24H2 for ARM64-based Systems	`5083769 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 24H2 for x64-based Systems	`5083769 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 25H2 for ARM64-based Systems	`5083769 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 25H2 for x64-based Systems	`5083769 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 26H1 for ARM64-based Systems	`5083768 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 version 26H1 for x64-based Systems	`5083768 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2016	`5082198 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2016 (Server Core installation)	`5082198 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2019	`5082123 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2019 (Server Core installation)	`5082123 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2022	`5082142 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2022 (Server Core installation)	`5082142 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2022, 23H2 Edition (Server Core installation)	`5082060 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2025	`5082063 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2025 (Server Core installation)	`5082063 (Security Update)`	Critical	Remote Code Execution	Yes

Patches

9 patches

Article	Type	Restart
`5082198`	Security Update	Yes
`5082123`	Security Update	Yes
`5082200`	Security Update	Yes
`5082052`	Security Update	Yes
`5083769`	Security Update	Yes
`5083768`	Security Update	Yes
`5082142`	Security Update	Yes
`5082060`	Security Update	Yes
`5082063`	Security Update	Yes

Patch Diff

ghidriff · ikeext.dll (KB5083769)

Remote, pre-auth double free (CWE-415) in the Windows IKE Extension service (ikeext.dll), reachable on UDP/500 and UDP/4500 with no authentication. During an IKE_SA_INIT exchange a Microsoft Security Realm Vendor ID payload makes IkeHandleSecurityRealmVendorId allocate a heap blob and store the pointer in the MMSA (Main Mode SA) at offset 0x208. When a fragmented IKE_AUTH message is reassembled, IkeReinjectReassembledPacket copies MMSA fields 0x178-0x21F (including the 0x208 blob pointer) into a stack struct, and IkeQueueRecvRequest shallow-copies it into a heap work item - so work_item+0xC8 ALIASES MMSA+0x208 (the reassembly buffer at 0x10 is deep-copied, but the blob pointer is not). Thread-pool processing calls IkeDestroyPacketContext -> WfpMemFree(work_item+0xC8) = FIRST free; later MMSA teardown (IkeCleanupMMNegotiation -> IkeDerefMMSA -> IkeFreeMMSA) frees MMSA+0x208 = SECOND free of the same allocation. Attacker sends IKE_SA_INIT (with the Security Realm Vendor ID) then >=2 SKF fragment payloads (type 0x35) carrying an invalid IKE_AUTH. Service runs as SYSTEM. IN-HOUSE ghidriff diff of 10.0.26100.7920 -> .8246 confirms the fix: IkeReinjectReassembledPacket now deep-copies the blob via IkeCopyBlob into a local and frees the COPY (not the aliased original), and IkeFreeMMSA/IkeBeginLifeExpireInplaceRekeyIkeV2 gain the same pattern - all GATED behind CFR flag Feature_3844326713, so both the aliasing and deep-copy paths ship in .8246. Credit: WARP & MORSE team at Microsoft; public analysis Richard Chen & Lucas Miller (TrendAI/ZDI).

Pre-patch version 10.0.26100.7920 Download

Post-patch version 10.0.26100.8246 Download

Function	Address	Change	Note
`IkeReinjectReassembledPacket`	`78% match`	code (deep-copy of Security Realm blob added, CFR-gated)	Pre: blob pointer at param_3[0x12] copied directly into the stack struct (local_50 = param_3[0x12]); only the reassembly buffer (local_108) was freed. Post (Feature_3844326713 enabled): local_50 zeroed, and if param_3[0x12] != 0 the blob is deep-copied via IkeCopyBlob into &uStack_58; at exit, when the feature is on and the queue request succeeded, WfpMemFree(&local_50) frees the COPY. Removes the alias between work_item+0xC8 and MMSA+0x208.
`IkeFreeMMSA`	`98% match`	code (feature-gated free of MMSA+0x208)	Updated with the same feature-gate pattern so MMSA+0x208 is only freed when the work item does not own a separate copy, preventing the second free.
`IkeBeginLifeExpireInplaceRekeyIkeV2`	`25% match`	code (same deep-copy pattern for the rekey path)	Adds IkeCopyBlob + WfpMemFree under Feature_3844326713 for the IKEv2 rekey path.
`IkeHandleSecurityRealmVendorId`		source (allocation site)	Allocates the Security Realm blob during IKE_SA_INIT and stores the pointer at MMSA+0x208 - the allocation that ends up double-freed.

View full diff report View RCA report

Attack Path

A Security Realm blob pointer is shallow-copied during IKEv2 fragment reassembly, aliasing the MMSA field and getting freed twice

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

WARP & MORSE team at Microsoft

References

MSRC Advisory MITRE NVD