CriticalCVE-2019-1367

    Microsoft Internet Explorer Scripting Engine Memory Corruption Vulnerability (CVE-2019-1367)

    Published In CISA KEV since Sources: CVE.org

    What is affected, what to do

    A remote code execution vulnerability exists in the way that the scripting engine handles objects in memory in Internet Explorer, aka 'Scripting Engine Memory Corruption Vulnerability'. This CVE ID is unique from CVE-2019-1221.

    The vulnerability is being actively exploited; treat it as a priority. CISA lists it as used in ransomware campaigns. The available sources name no fixed version. Check the vendor guidance in the references below. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Microsoft Internet Explorer 9 eq Windows Server 2008 for 32-bit Systems Service Pack 2..Windows Server 2008 for 32-bit Systems Service Pack 2
    • Microsoft Internet Explorer 9 eq Windows Server 2008 for x64-based Systems Service Pack 2..Windows Server 2008 for x64-based Systems Service Pack 2
    • Microsoft Internet Explorer 11 eq Windows 7 for 32-bit Systems Service Pack 1..Windows 7 for 32-bit Systems Service Pack 1
    • Microsoft Internet Explorer 11 eq Windows 7 for x64-based Systems Service Pack 1..Windows 7 for x64-based Systems Service Pack 1
    • Microsoft Internet Explorer 11 eq Windows Server 2008 R2 for x64-based Systems Service Pack 1..Windows Server 2008 R2 for x64-based Systems Service Pack 1
    • Microsoft Internet Explorer 11 eq Windows 8.1 for 32-bit systems..Windows 8.1 for 32-bit systems
    • Microsoft Internet Explorer 11 eq Windows 8.1 for x64-based systems..Windows 8.1 for x64-based systems
    • Microsoft Internet Explorer 11 eq Windows Server 2012 R2..Windows Server 2012 R2
    • Microsoft Internet Explorer 11 eq Windows 10 for 32-bit Systems..Windows 10 for 32-bit Systems
    • Microsoft Internet Explorer 11 eq Windows 10 for x64-based Systems..Windows 10 for x64-based Systems
    • Microsoft Internet Explorer 11 eq Windows Server 2016..Windows Server 2016
    • Microsoft Internet Explorer 11 eq Windows 10 Version 1607 for 32-bit Systems..Windows 10 Version 1607 for 32-bit Systems
    • Microsoft Internet Explorer 11 eq Windows 10 Version 1607 for x64-based Systems..Windows 10 Version 1607 for x64-based Systems
    • Microsoft Internet Explorer 11 eq Windows 10 Version 1703 for 32-bit Systems..Windows 10 Version 1703 for 32-bit Systems
    • Microsoft Internet Explorer 11 eq Windows 10 Version 1703 for x64-based Systems..Windows 10 Version 1703 for x64-based Systems
    • Microsoft Internet Explorer 11 eq Windows 10 Version 1709 for 32-bit Systems..Windows 10 Version 1709 for 32-bit Systems
    • Microsoft Internet Explorer 11 eq Windows 10 Version 1709 for x64-based Systems..Windows 10 Version 1709 for x64-based Systems
    • Microsoft Internet Explorer 11 eq Windows 10 Version 1803 for 32-bit Systems..Windows 10 Version 1803 for 32-bit Systems
    • Microsoft Internet Explorer 11 eq Windows 10 Version 1803 for x64-based Systems..Windows 10 Version 1803 for x64-based Systems
    • Microsoft Internet Explorer 11 eq Windows 10 Version 1803 for ARM64-based Systems..Windows 10 Version 1803 for ARM64-based Systems
    • Microsoft Internet Explorer 11 eq Windows 10 Version 1809 for 32-bit Systems..Windows 10 Version 1809 for 32-bit Systems
    • Microsoft Internet Explorer 11 eq Windows 10 Version 1809 for x64-based Systems..Windows 10 Version 1809 for x64-based Systems
    • Microsoft Internet Explorer 11 eq Windows 10 Version 1809 for ARM64-based Systems..Windows 10 Version 1809 for ARM64-based Systems
    • Microsoft Internet Explorer 11 eq Windows Server 2019..Windows Server 2019
    • Microsoft Internet Explorer 11 eq Windows 10 Version 1709 for ARM64-based Systems..Windows 10 Version 1709 for ARM64-based Systems
    • Microsoft Internet Explorer 10 eq Windows Server 2012..Windows Server 2012

    Not sure whether and how you are affected? Ask a question about this vulnerability

    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: CVE.org

    52.4 %

    EPSS score

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

    Source: FIRST EPSS, percentile 99.0

    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
    240.84 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 exploited
    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
    52.4 %
    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
    99.0
    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
    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
    CISA assessment (SSVC)
    Exploitation: active · not automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 7 February 2025
    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-787

    Response and mitigation

    Why act now?

    Prioritisation rationale

    The flaw is reachable over the network without authentication and only requires a user to load a crafted page. It was weaponised through drive-by downloads and exploit kits soon after disclosure. CISA flags it as used in ransomware campaigns, and exploitation likelihood is very high. Typical victims are organisations that still depend on IE or IE mode for legacy apps, such as public administration, manufacturing, healthcare and OT-adjacent operator stations, along with environments where patching lags. Treat any unpatched host with IE usage and internet access as critical and remediate immediately; hosts where the IE component is absent or removed can follow the normal patch cycle.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Deploy the security update: Microsoft shipped an out-of-band Internet Explorer update for CVE-2019-1367. A patch is available from the vendor; look up the KB number and target build per Windows version in the Microsoft Security Update Guide. Push it via WSUS, Intune or SCCM at top priority, clients first.
      • Scope the exposure: Find every host where iexplore.exe can still run or Edge IE mode is in use, including RDS/terminal servers, jump hosts, kiosks and OT HMI workstations. Use an EDR or inventory query to check the file version of %windir%\system32\jscript.dll and %windir%\SysWOW64\jscript.dll against the patched build.
      • Apply the workaround if you cannot patch: Microsoft's workaround is to restrict access to the legacy engine jscript.dll. From an elevated prompt, run takeown /f %windir%\system32\jscript.dll and cacls %windir%\system32\jscript.dll /E /P everyone:N, and repeat for %windir%\syswow64\jscript.dll on x64. IE11 uses jscript9.dll by default, but dependent applications may still break. Revert the workaround before you patch.
      • Kill IE usage: Enable the GPO "Disable Internet Explorer 11 as a standalone browser". Where there is no business need, remove the feature: Disable-WindowsOptionalFeature -Online -FeatureName Internet-Explorer-Optional-amd64.
      • Hunt for compromise: On unpatched hosts with IE activity, review the last few weeks of EDR telemetry for child processes of iexplore.exe (see Detection rules). On a hit, isolate the host and reset the affected user's credentials.

    2. Runbook step 2

      Mitigation layers

      • Configuration/application: Lock Edge IE mode to an enterprise site list that names only approved internal apps. Do not route internet destinations into IE mode.
      • Network/proxy: At the web proxy, block IE user agents (Trident/7.0, MSIE) to internet destinations, or allow them only to an allowlist of internal hosts. Deny uncategorised and newly registered domains for these user agents.
      • Endpoint hardening: Enable ASR rules, in particular "Block executable content from email client and webmail" and "Block process creations originating from PSExec and WMI commands". Add a WDAC/AppLocker rule that stops iexplore.exe from launching cmd.exe, powershell.exe, mshta.exe, wscript.exe or rundll32.exe.
      • IAM/least privilege: Code runs as the logged-on user. Remove local admin rights, keep privileged accounts off the browser, and block all internet browsing from privileged access workstations.
      • IE security zones: Disable or restrict "Active Scripting" for the Internet zone and enforce Enhanced Protected Mode via GPO.
      • Web gateway/IPS: Inspect HTML from external domains for content that forces the legacy engine, such as language="JScript.Encode", language="JScript.Compact" or <meta http-equiv="X-UA-Compatible" content="IE=EmulateIE8">.

    3. Runbook step 3

      Detection rules

      • Sysmon EID 1 / Security 4688 (process creation): ParentImage ends with \iexplore.exe and Image is a LOLBin. KQL: DeviceProcessEvents | where InitiatingProcessFileName =~ "iexplore.exe" and FileName in~ ("cmd.exe","powershell.exe","mshta.exe","wscript.exe","cscript.exe","rundll32.exe","regsvr32.exe")
      • Sysmon EID 7 (image load): Image ends with \iexplore.exe and ImageLoaded ends with \jscript.dll. Outside known legacy apps, this strongly suggests the legacy engine was forced. Sigma shape: selection: Image|endswith: '\iexplore.exe' AND ImageLoaded|endswith: '\jscript.dll', with a filter for approved internal hosts.
      • Sysmon EID 11 / EDR file events: iexplore.exe drops .exe, .dll, .hta or .ps1 files into %TEMP%, %APPDATA% or INetCache, followed by execution. SPL: index=sysmon EventCode=11 Image="*\\iexplore.exe" TargetFilename IN ("*.exe","*.dll","*.hta","*.ps1")
      • Proxy/Zeek HTTP: Look for an IE user agent hitting external hosts and then pulling executable content (Content-Type: application/octet-stream, application/x-msdownload) or starting to beacon. Also watch for multi-domain redirect chains, which are typical of exploit kits and malvertising.
      • Integrity monitoring: Alert on ACL changes to jscript.dll (Security 4670, or 4663 with a SACL in place). This verifies the workaround is in place and catches unauthorised reverts.

    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

    A remote code execution vulnerability exists in the way that the scripting engine handles objects in memory in Internet Explorer, aka 'Scripting Engine Memory Corruption Vulnerability'. This CVE ID is unique from CVE-2019-1221.

    Source: NVD (NIST), cvelistv5, CISA KEV Catalog

    Affected products

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

    Affected products
    Affected versionsFixed in
    MicrosoftInternet Explorer 10
    • Windows Server 2012
    • —
    MicrosoftInternet Explorer 11
    • Windows 7 for x64-based Systems Service Pack 1
    • Windows Server 2008 R2 for x64-based Systems Service Pack 1
    • Windows Server 2012 R2
    • Windows 10 Version 1809 for x64-based Systems
    • Windows Server 2016
    • Windows 10 Version 1703 for x64-based Systems
    • Windows 10 Version 1607 for 32-bit Systems
    • Windows 10 Version 1703 for 32-bit Systems
    • Windows 7 for 32-bit Systems Service Pack 1
    • Windows 8.1 for x64-based systems
    • Windows 10 Version 1809 for ARM64-based Systems
    • Windows 10 Version 1709 for 32-bit Systems
    • Windows 10 Version 1803 for x64-based Systems
    • Windows 10 for 32-bit Systems
    • Windows 10 Version 1709 for ARM64-based Systems
    • Windows 10 Version 1709 for x64-based Systems
    • Windows Server 2019
    • Windows 10 Version 1809 for 32-bit Systems
    • Windows 8.1 for 32-bit systems
    • Windows 10 Version 1803 for ARM64-based Systems
    • Windows 10 for x64-based Systems
    • Windows 10 Version 1803 for 32-bit Systems
    • Windows 10 Version 1607 for x64-based Systems
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    MicrosoftInternet Explorer 9
    • Windows Server 2008 for x64-based Systems Service Pack 2
    • Windows Server 2008 for 32-bit Systems Service Pack 2
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    microsoftinternet_explorer
    • 9
    • 10
    • 11
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    Vendors and products

    Weakness classes (CWE)

    • CWE-787Out-of-bounds Write

      Base

      The product writes data past the end, or before the beginning, of the intended buffer.

      Entry at MITRE CWE-787

    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 CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited

    References & sources

    • portal.msrc.microsoft.comen-US/security-guidance/advisory/CVE-2019-1367x_refsource_MISC, Patch, Vendor advisory
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2019-1367government-resource, US government resource
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