CriticalCVE-2026-33824

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

Published 14.04.2026Last modified 25.09.2026In CISA KEV since 18.08.2026Sources: Msrc Update Guide, pwn.watch, CVE.org, SingCERT, EUVD, BSI

What is affected, what to do

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

The vulnerability is being actively exploited; treat it as a priority. Update Microsoft Windows 10 Version 1607 to version 10.0.14393.9060, Microsoft Windows 10 Version 1809 to version 10.0.17763.8644, Microsoft Windows 10 Version 21H2 to version 10.0.19044.7184. Immediate actions, mitigation and detection rules are in the runbook below.

Affected: Microsoft Windows 10 Version 1607 lt 10.0.14393.0..10.0.14393.9060
Microsoft Windows 10 Version 1809 lt 10.0.17763.0..10.0.17763.8644
Microsoft Windows 10 Version 21H2 lt 10.0.19044.0..10.0.19044.7184
Microsoft Windows 10 Version 22H2 lt 10.0.19045.0..10.0.19045.7184
Microsoft Windows 11 version 23H2 lt 10.0.22631.0..10.0.22631.6936
Microsoft Windows 11 Version 24H2 lt 10.0.26100.0..10.0.26100.8246
Microsoft Windows 11 Version 25H2 lt 10.0.26200.0..10.0.26200.8246
Microsoft Windows 11 version 26H1 lt 10.0.28000.0..10.0.28000.1836
Microsoft Windows Server 2016 lt 10.0.14393.0..10.0.14393.9060
Microsoft Windows Server 2016 (Server Core installation) lt 10.0.14393.0..10.0.14393.9060
Microsoft Windows Server 2019 lt 10.0.17763.0..10.0.17763.8644
Microsoft Windows Server 2019 (Server Core installation) lt 10.0.17763.0..10.0.17763.8644
Microsoft Windows Server 2022 lt 10.0.20348.0..10.0.20348.5020
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) lt 10.0.25398.0..10.0.25398.2274
Microsoft Windows Server 2025 lt 10.0.26100.0..10.0.26100.32690
Microsoft Windows Server 2025 (Server Core installation) lt 10.0.26100.0..10.0.26100.32690
Fixed in: Microsoft Windows 10 Version 1607 10.0.14393.9060
Microsoft Windows 10 Version 1809 10.0.17763.8644
Microsoft Windows 10 Version 21H2 10.0.19044.7184
Microsoft Windows 10 Version 22H2 10.0.19045.7184
Microsoft Windows 11 version 23H2 10.0.22631.6936
Microsoft Windows 11 Version 24H2 10.0.26100.8246
Microsoft Windows 11 Version 25H2 10.0.26200.8246
Microsoft Windows 11 version 26H1 10.0.28000.1836
Microsoft Windows Server 2016 10.0.14393.9060
Microsoft Windows Server 2016 (Server Core installation) 10.0.14393.9060
Microsoft Windows Server 2019 10.0.17763.8644
Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.8644
Microsoft Windows Server 2022 10.0.20348.5020
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.2274
Microsoft Windows Server 2025 10.0.26100.32690
Microsoft Windows Server 2025 (Server Core installation) 10.0.26100.32690

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Metrics

9.8

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: NVD, CVSS v3

9.8

CVSS v3

Severity Critical on the scale from 0 to 10.

Source: Msrc Update Guide, pwn.watch, CVE.org, SingCERT, EUVD, BSI

77.1 %

EPSS score

High — model estimates ≥ 50% chance of real-world exploitation within 30 days.

Source: FIRST EPSS, percentile 99.55

Show all metrics

Severity: Critical
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 244.60 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: actively exploitedSource: VulnCheck KEV (opens in a new tab) How we classify
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 9.8 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 9.8
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 77.1 %; High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 99.55; Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: Actively exploited
Published: 14.04.2026
In CISA KEV since The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: 18.08.2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-415

Response and mitigation

Why act now?

Prioritisation rationale

This flaw is reachable over the network with no authentication and no user interaction, and yields code execution inside a system service. That is the classic profile of a wormable pre-auth RCE, and its KEV listing confirms real-world exploitation. The modelled exploitation likelihood is currently moderate, and CISA does not flag known ransomware use. Typical targets are internet-facing Windows VPN gateways (RRAS, Always On VPN, DirectAccess) and flat internal networks where an intruder can pivot laterally over UDP 500/4500. If IKE is reachable at your perimeter, treat this as critical and patch or block within 24 hours; client fleets with no inbound IKE exposure can follow in an accelerated but regular patch cycle.

01
Runbook step 1
Immediate response (0-24 h)
- Find exposed hosts first: Inventory every Windows host with inbound-reachable UDP 500 (IKE) and UDP 4500 (IKE NAT-T), using external scans (nmap -sU -p 500,4500) and a firewall rule review. Internet-facing RRAS/VPN gateways and DirectAccess servers come first.
- Deploy the Microsoft security update: Patches are available for these minimum fixed builds:
  
  Win10 1607: 10.0.14393.9060
  
  1809: 10.0.17763.8644
  
  21H2: 10.0.19044.7184
  
  22H2: 10.0.19045.7184
  
  Win11 23H2: 10.0.22631.6936
  
  24H2: 10.0.26100.8246
  
  25H2: 10.0.26200.8246
  
  26H1: 10.0.28000.1836
  
  Look up the KB number in the Microsoft Security Update Guide. Explicitly confirm Server editions sharing the 14393/17763/26100 build lines against the advisory.
- Verify the build level: Check fleet status via Intune/SCCM/Defender TVM, e.g. Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion' | Select CurrentBuild,UBR. Treat anything below the fixed UBR as vulnerable.
- If patching lags, disable the service. Where IPsec/IKEv2 VPN is not needed, run Stop-Service IKEEXT; Set-Service IKEEXT -StartupType Disabled immediately. Check dependencies before you do: Always On VPN (IKEv2), DirectAccess, IPsec connection security rules and AuthIP.
- Block inbound traffic: Drop UDP 500/4500 at the perimeter for every host that is not a designated VPN endpoint.
02
Runbook step 2
Mitigation layers
- Network segmentation: Permit IKE only from known peer IPs (site-to-site partners, known gateways). Block east-west UDP 500/4500 between client VLANs to deny lateral exploitation.
- Host firewall (GPO): Push a Windows Defender Firewall rule "Block Inbound UDP 500,4500" to all clients and servers without an IPsec role. On VPN gateways, scope the rule to allowed remote addresses.
- IPS/network: Enable IPS signatures for malformed or abnormally fragmented IKEv1/IKEv2 traffic (IKEv2 fragmentation abuse, oversized payloads, repeated SA_INIT bursts from one source). Pull vendor signatures for CVE-2026-33824 as soon as they ship.
- Architecture: Where feasible, front or replace Windows RRAS as the internet VPN terminator with a separately patched gateway.
- Endpoint hardening: Set EDR protection for the IKEEXT svchost.exe instance to block mode, especially rules covering code injection and unexpected child processes. Enable ASR rules.
- Recovery behaviour: A double free mostly manifests as crashes first. Monitor service recovery settings, because silent auto-restarts can hide repeated exploitation attempts.
03
Runbook step 3
Detection rules
- IKEEXT service crashes:
  
  System log: Event ID 7031/7034 for the service "IKE and AuthIP IPsec Keying Modules".
  
  Application log: Event ID 1000/1001 (WER) with Faulting module name: ikeext.dll.
  
  Clustered crashes are a strong signal of exploit attempts.
  
  KQL: Event | where EventID in (1000,1001) and RenderedDescription has "ikeext.dll"
- Suspicious process ancestry: Sysmon EID 1 or EDR events with parent svchost.exe -k netsvcs -p -s IKEEXT spawning cmd.exe, powershell.exe, rundll32.exe or mshta.exe.
  
  Sigma shape: ParentCommandLine|contains: 'IKEEXT' AND Image|endswith: ['\cmd.exe','\powershell.exe','\rundll32.exe']
- IPsec auditing: Watch for high-volume Event ID 4653 (main mode negotiation failed) and 4654 (quick mode failed) from unknown sources. This requires the "IPsec Main Mode/Extended Mode" audit policy. Correlate with WFP events 5156/5152 on UDP 500/4500.
- Network (Zeek/Suricata): Flag inbound IKE from addresses outside the peer allowlist, oversized or heavily fragmented IKEv2 packets, and IKE traffic to hosts without a VPN role. In Zeek, match conn.log entries with proto==udp and id.resp_p in {500,4500} against the allowlist.
- Post-exploitation: Look for new outbound connections from the IKEEXT svchost.exe to internet addresses on ports other than UDP 500/4500 (Sysmon EID 3).

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

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

Source: Microsoft Security Update Guide, pwn.watch, cvelistv5, NVD (NIST), CISA KEV Catalog, CVE.org (MITRE), CSA/SingCERT, ENISA EUVD, BSI WID Portal, BSI CSAF

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
Microsoft	Windows 10 Version 1607	`10.0.14393.0 – < 10.0.14393.9060`	`10.0.14393.9060`
Microsoft	Windows 10 Version 1809	`10.0.17763.0 – < 10.0.17763.8644`	`10.0.17763.8644`
Microsoft	Windows 10 Version 21H2	`10.0.19044.0 – < 10.0.19044.7184`	`10.0.19044.7184`
Microsoft	Windows 10 Version 22H2	`10.0.19045.0 – < 10.0.19045.7184`	`10.0.19045.7184`
Microsoft	Windows 11 version 23H2	`10.0.22631.0 – < 10.0.22631.6936`	`10.0.22631.6936`
Microsoft	Windows 11 Version 24H2	`10.0.26100.0 – < 10.0.26100.8246`	`10.0.26100.8246`
Microsoft	Windows 11 Version 25H2	`10.0.26200.0 – < 10.0.26200.8246`	`10.0.26200.8246`
Microsoft	Windows 11 version 26H1	`10.0.28000.0 – < 10.0.28000.1836`	`10.0.28000.1836`
Microsoft	Windows Server 2016	`10.0.14393.0 – < 10.0.14393.9060`	`10.0.14393.9060`
Microsoft	Windows Server 2016 (Server Core installation)	`10.0.14393.0 – < 10.0.14393.9060`	`10.0.14393.9060`
Microsoft	Windows Server 2019	`10.0.17763.0 – < 10.0.17763.8644`	`10.0.17763.8644`
Microsoft	Windows Server 2019 (Server Core installation)	`10.0.17763.0 – < 10.0.17763.8644`	`10.0.17763.8644`
Microsoft	Windows Server 2022	`10.0.20348.0 – < 10.0.20348.5020`	`10.0.20348.5020`
Microsoft	Windows Server 2022, 23H2 Edition (Server Core installation)	`10.0.25398.0 – < 10.0.25398.2274`	`10.0.25398.2274`
Microsoft	Windows Server 2025	`10.0.26100.0 – < 10.0.26100.32690`	`10.0.26100.32690`
Microsoft	Windows Server 2025 (Server Core installation)	`10.0.26100.0 – < 10.0.26100.32690`	`10.0.26100.32690`
Xerox	FreeFlow Print Server	`v7` `v2`	— —

Vendors and products

Affected operating systems

Affected operating systems

Windows	microsoft	windows_10_1607	—
Windows	microsoft	windows_10_1809	—
Windows	microsoft	windows_10_21h2	—
Windows	microsoft	windows_10_22h2	—
Windows	microsoft	windows_11_23h2	—
Windows	microsoft	windows_11_24h2	—
Windows	microsoft	windows_11_25h2	—
Windows	microsoft	windows_11_26h1	—
Windows	microsoft	windows_server_2016	—
Windows	microsoft	windows_server_2019	—
Windows	microsoft	windows_server_2022	—
Windows	microsoft	windows_server_2022_23h2	—
Windows	microsoft	windows_server_2025	—

Weakness classes (CWE)

CWE-415Double Free
Variant
The product calls free() twice on the same memory address.
Entry at MITRE CWE-415

Public exploit references

Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

Public exploit references

CISA KEV Catalog	CISA Known Exploited Vulnerability (opens in a new tab)cisa.gov	actively exploited	18.08.2026
PoC-in-GitHub (nomi-sec)	IKEV2-POC (opens in a new tab)github.com	PoC (publicly reported)reported, not verified	18.05.2026

References & sources

Microsoft Security Update GuideWindows Internet Key Exchange (IKE) Service Extensions Remote Code Execution Vulnerabilityeuvd, Vendor advisory, Patch
unit42.paloaltonetworks.comautonomous-ai-cyber-attack-campaignThird-party advisory
cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2026-33824government-resource
pwn.watchpwn.watch: Microsoft Internet Key Exchange (IKE) Service Extensions: Microsoft Internet Key Exchange (IKE) Service Extensions Double Free Vulnerabilitypwn-watch
Microsoft Security Update GuideMicrosoft Internet Key Exchange (IKE) Service Extensions — CVE-2026-33824pwn-watch
NVD (NIST)NVD: CVE-2026-33824pwn-watch
cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

25.09.2026Record modifiedMicrosoft

New references:

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33824

Show 4 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Affected versions (publisher)	added	—	Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/33xxx/CVE-2026-33824.json">CVE-2026-33824</a>
Reference	added	—	https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33824
Reference	removed	https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33824	—
Reference type	removed	https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33824 Types: Vendor Advisory	—

Source identifier: secure@microsoft.com

25.09.2026Record modifiedCISA ADP

New references:

Show 6 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://unit42.paloaltonetworks.com/autonomous-ai-cyber-attack-campaign/
Reference	added	—	https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-33824
Reference	removed	https://unit42.paloaltonetworks.com/autonomous-ai-cyber-attack-campaign/	—
Reference	removed	https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-33824	—
Reference type	removed	https://unit42.paloaltonetworks.com/autonomous-ai-cyber-attack-campaign/ Types: Third Party Advisory	—
Reference type	removed	https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-33824 Types: US Government Resource	—

Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

19.08.2026Record modifiedCISA ADP

CISA assessment (SSVC): exploitation: active, automatable: yes

Show the original change

Individual changes of this event as published by NVD
Type	Action	Before	After
SSVC assessment	changed	{"id":"CVE-2026-33824","role":"CISA Coordinator","options":[{"exploitation":"active"},{"automatable":"yes"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-08-18T17:44:04.148157Z"}	{"id":"CVE-2026-33824","role":"CISA Coordinator","options":[{"exploitation":"active"},{"automatable":"yes"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-04-13T00:00:00+00:00"}

Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

One NVD translation into another language is hidden.

Linked advisories

@RISK®: The Consensus Security Vulnerability Alert: Vol. 26, Num. 32SANS @RISK20.08.2026

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<a href="https://intel.neosec.eu/en/cve/CVE-2026-33824"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-33824.svg?lang=en" alt="CVE-2026-33824 – NEOSEC Intel" height="20"></a>

What is affected, what to do

Metrics

Response and mitigation

Prioritisation rationale

Immediate response (0-24 h)

Mitigation layers

Detection rules

Detection rules

Classification under NIS2 and CRA

Description

Affected products

Vendors and products

Affected operating systems

Weakness classes (CWE)

Public exploit references

References & sources

Changes to this CVE

Linked advisories