CriticalCVE-2023-36884

Windows Search Remote Code Execution Vulnerability (CVE-2023-36884)

Published 11.07.2023Last modified 10.08.2026In CISA KEV since 17.07.2023Sources: SingCERT, pwn.watch, CVE.org

Actively exploited
Source: ANSSI / CERT-FR, CSA/SingCERT How we classify
Ransomware

What is affected, what to do

Windows Search Remote Code Execution Vulnerability

The vulnerability is being actively exploited; treat it as a priority. CISA lists it as used in ransomware campaigns. Update Microsoft Windows 10 Version 1507 to version 10.0.10240.20107, Microsoft Windows 10 Version 1607 to version 10.0.14393.6167, Microsoft Windows 10 Version 1809 to version 10.0.17763.4737. Immediate actions, mitigation and detection rules are in the runbook below.

Affected: Microsoft Windows 10 Version 1507 lt 10.0.10240.0..10.0.10240.20107
Microsoft Windows 10 Version 1607 lt 10.0.14393.0..10.0.14393.6167
Microsoft Windows 10 Version 1809 lt 10.0.17763.0..10.0.17763.4737
Microsoft Windows 10 Version 21H2 lt 10.0.19044.0..10.0.19044.3324
Microsoft Windows 10 Version 22H2 lt 10.0.19045.0..10.0.19045.3324
Microsoft Windows 11 version 21H2 lt 10.0.22000.0..10.0.22000.2295
Microsoft Windows 11 version 22H2 lt 10.0.22621.0..10.0.22621.2134
Microsoft Windows Server 2008 Service Pack 2 lt 6.0.6003.0..6.0.6003.22216
Microsoft Windows Server 2008 R2 Service Pack 1 lt 6.1.7601.0..6.1.7601.26664
Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation) lt 6.1.7601.0..6.1.7601.26664
Microsoft Windows Server 2008 Service Pack 2 (Server Core installation) lt 6.0.6003.0..6.0.6003.22216
Microsoft Windows Server 2012 lt 6.2.9200.0..6.2.9200.24414
Microsoft Windows Server 2012 (Server Core installation) lt 6.2.9200.0..6.2.9200.24414
Microsoft Windows Server 2012 R2 lt 6.3.9600.0..6.3.9600.21503
Microsoft Windows Server 2012 R2 (Server Core installation) lt 6.3.9600.0..6.3.9600.21503
Microsoft Windows Server 2016 lt 10.0.14393.0..10.0.14393.6167
Microsoft Windows Server 2016 (Server Core installation) lt 10.0.14393.0..10.0.14393.6167
Microsoft Windows Server 2019 lt 10.0.17763.0..10.0.17763.4737
Microsoft Windows Server 2019 (Server Core installation) lt 10.0.17763.0..10.0.17763.4737
Microsoft Windows Server 2022 lt 10.0.20348.0..10.0.20348.1906
Fixed in: Microsoft Windows 10 Version 1507 10.0.10240.20107
Microsoft Windows 10 Version 1607 10.0.14393.6167
Microsoft Windows 10 Version 1809 10.0.17763.4737
Microsoft Windows 10 Version 21H2 10.0.19044.3324
Microsoft Windows 10 Version 22H2 10.0.19045.3324
Microsoft Windows 11 version 21H2 10.0.22000.2295
Microsoft Windows 11 version 22H2 10.0.22621.2134
Microsoft Windows Server 2008 Service Pack 2 6.0.6003.22216
Microsoft Windows Server 2008 R2 Service Pack 1 6.1.7601.26664
Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation) 6.1.7601.26664
Microsoft Windows Server 2008 Service Pack 2 (Server Core installation) 6.0.6003.22216
Microsoft Windows Server 2012 6.2.9200.24414
Microsoft Windows Server 2012 (Server Core installation) 6.2.9200.24414
Microsoft Windows Server 2012 R2 6.3.9600.21503
Microsoft Windows Server 2012 R2 (Server Core installation) 6.3.9600.21503
Microsoft Windows Server 2016 10.0.14393.6167
Microsoft Windows Server 2016 (Server Core installation) 10.0.14393.6167
Microsoft Windows Server 2019 10.0.17763.4737
Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.4737
Microsoft Windows Server 2022 10.0.20348.1906

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Metrics

7.5

Priority

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

Source: NVD, CVSS v3

7.5

CVSS v3

Severity High on the scale from 0 to 10.

Source: SingCERT, pwn.watch, CVE.org

99.44 %

EPSS score

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

Source: FIRST EPSS, percentile 99.94

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: 245.42 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: ANSSI / CERT-FR, CSA/SingCERT 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: 7.5 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: 7.5
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: 99.44 %; 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: 99.94; 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: 11.07.2023
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: 17.07.2023
CISA assessment (SSVC): Exploitation: active · not automatable · Technical impact: total; Source: CISA Vulnrichment, as of 9 December 2023
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-362

Response and mitigation

Why act now?

Prioritisation rationale

This flaw is network-reachable without authentication and only needs a user to open a crafted file. A successful exploit gives full confidentiality, integrity and availability impact on the endpoint. The nominally high attack complexity is neutralised in practice by ready-made phishing lures. CISA flags known ransomware campaign use, and its exploitation likelihood sits among the very highest of all tracked CVEs. Typical targets are organisations with heavy inbound external email, notably government, defence and critical-infrastructure-adjacent entities. Treat every unpatched Windows client running Office as critical, and put patch rollout plus SMB/WebDAV egress blocking ahead of lower-likelihood server patching.

01
Runbook step 1
Immediate response (0-24 h)
- Deploy the August 2023 security update: Microsoft fixed this in the August 2023 Patch Tuesday release. The patch is available from the vendor; look up the exact KB per Windows version in the CVE-2023-36884 vendor advisory. The context references builds including 10.0.10240.20107 (1507), 10.0.14393.6167 (1607), 10.0.17763.4737 (1809) and 10.0.19044.3324 (21H2/22H2). Treat anything below these builds as vulnerable and push via WSUS/Intune/ConfigMgr with high priority.
- Install the Office defence-in-depth update as well: The attack chain is delivered through weaponised Office documents. Bring Office/Microsoft 365 Apps to the current build of their update channel alongside the Windows patch.
- Set the registry block where patching lags: Under HKLM\SOFTWARE\Policies\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BLOCK_CROSS_PROTOCOL_FILE_NAVIGATION, add a DWORD value of 1 for each Office binary (Winword.exe, Excel.exe, Powerpnt.exe, Outlook.exe, Visio.exe, MSPub.exe, WordPad.exe, Wordview.exe). Deploy it via GPO, and test the impact on documents with linked content first.
- Retro-hunt inbound mail: Sweep recent mailboxes for Office/RTF attachments and for ZIP/ISO containers wrapping Office files. Quarantine hits and detonate them in a sandbox.
- Block outbound SMB/WebDAV: Deny TCP 445/139 and WebDAV (HTTP/HTTPS PROPFIND) from clients to the internet at the perimeter. The chain fetches follow-on payloads from attacker-controlled shares.
02
Runbook step 2
Mitigation layers
- Network: Apply egress filtering for SMB (TCP 445/139) and WebDAV verbs from workstation VLANs to the internet. Log every deny as well as blocking it. An Office client reaching an external SMB share is a high-fidelity compromise signal.
- Endpoint hardening (Defender ASR): Enable "Block all Office applications from creating child processes" (d4f940ab-401b-4efc-aadc-ad5f3c50688a) in block mode. Add "Block Office applications from creating executable content" and "Block Win32 API calls from Office macros".
- Office configuration: Enforce Protected View for internet-origin files and attachments via GPO. Set File Block for RTF and legacy formats to open in Protected View or block. Block macros from the internet.
- Mail gateway: Route RTF, DOCX with external altChunk/OLE references, and nested archives (ZIP/ISO/IMG) to sandbox detonation. Focus on documents that reference external URLs or UNC paths on open.
- Protocol handler: Where business impact allows, unregister the search-ms:/search: handler via registry (HKCR\search-ms; export it first). This removes a common payload-staging path.
- Least privilege: Remove local admin rights on Office workstations to limit post-execution impact.
03
Runbook step 3
Detection rules
- Sysmon EID 1 / EDR process ancestry: Watch for WINWORD.EXE/EXCEL.EXE/POWERPNT.EXE spawning cmd.exe, powershell.exe, mshta.exe, rundll32.exe, regsvr32.exe or wscript.exe. KQL: DeviceProcessEvents | where InitiatingProcessFileName in~ ("winword.exe","excel.exe","powerpnt.exe") and FileName in~ ("cmd.exe","powershell.exe","mshta.exe","rundll32.exe").
- Sysmon EID 3 / Zeek conn.log: Look for outbound TCP 445 or WebDAV (PROPFIND, User-Agent Microsoft-WebDAV-MiniRedir) to external IPs initiated by Office or by the WebClient svchost.exe. Sigma shape: Image|endswith: '\winword.exe' AND DestinationPort: 445 AND DestinationIp NOT in RFC1918.
- Search protocol abuse: Flag process creation where explorer.exe or an Office binary carries search-ms:/search: in the command line, especially with crumb=location:\\ or remote UNC paths.
- Sysmon EID 11 / EID 15: Look for files dropped by Office into %TEMP% or INetCache (.url, .lnk, .hta, .js, .zip) without a Zone.Identifier stream. This indicates a Mark of the Web bypass.
- DNS (Sysmon EID 22 / resolver logs): Flag first-seen rare domains resolved by winword.exe immediately after a document opens. Correlate with mail delivery within a few minutes.

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

Windows Search Remote Code Execution Vulnerability

Source: CSA/SingCERT, pwn.watch, CISA KEV Catalog, NVD (NIST), cvelistv5, CVE.org (MITRE)

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 1507	`10.0.10240.0 – < 10.0.10240.20107`	`10.0.10240.20107`
Microsoft	Windows 10 Version 1607	`10.0.14393.0 – < 10.0.14393.6167`	`10.0.14393.6167`
Microsoft	Windows 10 Version 1809	`10.0.17763.0 – < 10.0.17763.4737`	`10.0.17763.4737`
Microsoft	Windows 10 Version 21H2	`10.0.19044.0 – < 10.0.19044.3324`	`10.0.19044.3324`
Microsoft	Windows 10 Version 22H2	`10.0.19045.0 – < 10.0.19045.3324`	`10.0.19045.3324`
Microsoft	Windows 11 version 21H2	`10.0.22000.0 – < 10.0.22000.2295`	`10.0.22000.2295`
Microsoft	Windows 11 version 22H2	`10.0.22621.0 – < 10.0.22621.2134`	`10.0.22621.2134`
Microsoft	Windows Server 2008 R2 Service Pack 1	`6.1.7601.0 – < 6.1.7601.26664`	`6.1.7601.26664`
Microsoft	Windows Server 2008 R2 Service Pack 1 (Server Core installation)	`6.1.7601.0 – < 6.1.7601.26664`	`6.1.7601.26664`
Microsoft	Windows Server 2008 Service Pack 2	`6.0.6003.0 – < 6.0.6003.22216`	`6.0.6003.22216`
Microsoft	Windows Server 2008 Service Pack 2 (Server Core installation)	`6.0.6003.0 – < 6.0.6003.22216`	`6.0.6003.22216`
Microsoft	Windows Server 2012	`6.2.9200.0 – < 6.2.9200.24414`	`6.2.9200.24414`
Microsoft	Windows Server 2012 (Server Core installation)	`6.2.9200.0 – < 6.2.9200.24414`	`6.2.9200.24414`
Microsoft	Windows Server 2012 R2	`6.3.9600.0 – < 6.3.9600.21503`	`6.3.9600.21503`
Microsoft	Windows Server 2012 R2 (Server Core installation)	`6.3.9600.0 – < 6.3.9600.21503`	`6.3.9600.21503`
Microsoft	Windows Server 2016	`10.0.14393.0 – < 10.0.14393.6167`	`10.0.14393.6167`
Microsoft	Windows Server 2016 (Server Core installation)	`10.0.14393.0 – < 10.0.14393.6167`	`10.0.14393.6167`
Microsoft	Windows Server 2019	`10.0.17763.0 – < 10.0.17763.4737`	`10.0.17763.4737`
Microsoft	Windows Server 2019 (Server Core installation)	`10.0.17763.0 – < 10.0.17763.4737`	`10.0.17763.4737`
Microsoft	Windows Server 2022	`10.0.20348.0 – < 10.0.20348.1906`	`10.0.20348.1906`

Vendors and products

Affected operating systems

Affected operating systems

Windows	microsoft	windows_10_1507	—
Windows	microsoft	windows_10_1607	—
Windows	microsoft	windows_10_1809	—
Windows	microsoft	windows_10_21h2	—
Windows	microsoft	windows_10_22h2	—
Windows	microsoft	windows_11_21h2	—
Windows	microsoft	windows_11_22h2	—
Windows	microsoft	windows_server_2008	`r2`
Windows	microsoft	windows_server_2008	—
Windows	microsoft	windows_server_2012	`r2`
Windows	microsoft	windows_server_2012	—
Windows	microsoft	windows_server_2016	—
Windows	microsoft	windows_server_2019	—
Windows	microsoft	windows_server_2022	—

Weakness classes (CWE)

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Class
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
Entry at MITRE CWE-362

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	17.07.2023
CSA/SingCERT	Active Exploitation of Zero-Day Vulnerability Affecting Microsoft Office & Windows (opens in a new tab)CSA/SingCERT	actively exploited	13.08.2023
CSA/SingCERT	July 2023 Monthly Patch (opens in a new tab)CSA/SingCERT	actively exploited	11.07.2023
ANSSI / CERT-FRLicence Ouverte 2.0, as of 12.12.2023	CERTFR-2023-ALE-006 – Vulnérabilité dans les produits Microsoft (clôturée 2023-12-12) (opens in a new tab)cert.cyber.gouv.fr	actively exploited	12.07.2023

References & sources

Microsoft Security Update GuideWindows Search Remote Code Execution VulnerabilityVendor advisory, Patch, pwn-watch
seclists.orgfulldisclosure/2023/Jul/43x_transferred
cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2023-36884government-resource
cert.cyber.gouv.frANSSI / CERT-FR: CERTFR-2023-ALE-006 – Vulnérabilité dans les produits Microsoft (clôturée 2023-12-12)cert-fr
pwn.watchpwn.watch: Microsoft Windows: Search Remote Code Execution (CVE-2023-36884)pwn-watch
NVD (NIST)NVD: CVE-2023-36884pwn-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).

10.08.2026Record modifiedMicrosoft

1 individual change: Affected versions (publisher)

Show the original change

Individual changes of this event as published by NVD
Type	Action	Before	After
Affected versions (publisher)	changed	Windows 10 Version 1809, Windows 10 Version 1809, Windows Server 2019 (+19)	Windows 10 Version 1507, Windows 10 Version 1607, Windows 10 Version 1809 (+19)

Source identifier: secure@microsoft.com

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<a href="https://intel.neosec.eu/en/cve/CVE-2023-36884"><img src="https://intel.neosec.eu/badge/cve/CVE-2023-36884.svg?lang=en" alt="CVE-2023-36884 – 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