CriticalCVE-2018-8298

    ChakraCore Scripting Engine Type Confusion Vulnerability (CVE-2018-8298)

    Published In CISA KEV since Sources: CVE.org, OSV

    What is affected, what to do

    A remote code execution vulnerability exists in the way that the ChakraCore scripting engine handles objects in memory, aka "Scripting Engine Memory Corruption Vulnerability." This affects ChakraCore. This CVE ID is unique from CVE-2018-8242, CVE-2018-8283, CVE-2018-8287, CVE-2018-8288, CVE-2018-8291, CVE-2018-8296.

    The vulnerability is being actively exploited; treat it as a priority. Update chakracore to version 1.10.1. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Microsoft ChakraCore eq ChakraCore..ChakraCore

    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, OSV

    74.7 %

    EPSS score

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

    Source: FIRST EPSS, percentile 99.50

    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
    216.70 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.

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    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“.

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    74.7 %
    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.

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    99.50
    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-843

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This sits on KEV because type confusion in JavaScript engines is a proven way to turn crafted script content into code execution in the host process. It is network-reachable without authentication, but it needs user interaction or the processing of attacker-supplied script, and exploitation is non-trivial. Exploitation likelihood is nonetheless rated very high, and CISA does not flag known ransomware use. Rank it high if you ship or buy applications that embed ChakraCore to run external script. If the engine is absent, completing the inventory closes the risk. Because the engine is out of support, treat any remaining use as technical debt with a migration deadline.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Inventory the embedded engine: ChakraCore is a library, not a standalone product. Sweep file systems and repos for ChakraCore.dll, libChakraCore.so and libChakraCore.dylib. Grep packages.config, *.csproj and *.nuspec for Microsoft.ChakraCore, and check Node projects for node-chakracore. Prioritise the affected NuGet versions 1.2.0, 1.2.1, 1.2.2, 1.2.3, 1.2.6.62716-preview and 1.3.0.
      • Upgrade to ChakraCore 1.10.1 or later: 1.10.1 contains the fix for CVE-2018-8298. Rebuild or repackage and redeploy every application on an older build. Include statically linked copies inside third-party software and ask those vendors for updated releases.
      • Check support status: Microsoft no longer ships security updates for the 1.x line. Apps that run untrusted script through ChakraCore need a migration plan to a maintained engine such as V8. Upgrading to 1.10.1 only addresses this CVE and earlier ones.
      • Isolate exposed hosts: Take unpatched apps that process external script content (web content, plugins, user scripts, bot or automation engines) offline, or disable that feature until they are updated.
      • Check legacy hosts with EdgeHTML/Chakra components: Verify these against the July 2018 Microsoft security update round. Look up the KB number in the vendor advisory.

    2. Runbook step 2

      Mitigation layers

      • Application configuration: If you cannot upgrade, create the runtime with JsRuntimeAttributeDisableNativeCodeGeneration to turn off the JIT, where type confusion bugs commonly live. Also set JsRuntimeAttributeDisableEval. This reduces risk but is not a guaranteed fix.
      • Input control: Restrict script execution to signed or internally approved sources. Never feed user-supplied or internet-sourced script into an unpatched engine.
      • Endpoint hardening: Run the host process with least privilege, on Windows inside an AppContainer or at low integrity. Enforce CFG, DEP and mandatory/bottom-up ASLR via Windows Exploit Protection. Use WDAC/AppLocker to stop the host process from launching arbitrary binaries.
      • Network segmentation: Move servers that embed the engine into a dedicated segment. Apply strict egress filtering to approved destinations only, which blocks second-stage downloads and C2 after a successful exploit.
      • Proxy/content filtering: On the secure web gateway, block JavaScript from uncategorised or newly registered domains for clients running affected components. Enable your IPS vendor's signatures for exploit-kit landing pages (signature category "browser/scripting engine memory corruption").
      • Supply chain: Add an SCA gate to CI/CD (e.g. dotnet list package --vulnerable, OWASP Dependency-Check) that fails any build pulling Microsoft.ChakraCore < 1.10.1.

    3. Runbook step 3

      Detection rules

      • Crash telemetry: Watch the Windows Application log for Event ID 1000/1001 with Faulting module name: ChakraCore.dll. Clusters of crashes often mean failed exploit attempts. KQL: Event | where EventID == 1000 and RenderedDescription has "ChakraCore.dll".
      • Image-load inventory: Sysmon EID 7 with ImageLoaded endswith "\\ChakraCore.dll" shows every process that loads the engine. Escalate unexpected host processes or load paths such as %TEMP% or user profiles.
      • Process ancestry: Alert on Sysmon EID 1 or Security EID 4688 when a ChakraCore-hosting process spawns cmd.exe, powershell.exe, rundll32.exe, mshta.exe or regsvr32.exe. Sigma shape: ParentImage in [<host-app inventory>] AND Image endswith [cmd.exe, powershell.exe, …].
      • Network anomalies: In Zeek/Suricata, flag new outbound connections from engine-hosting servers to unknown external destinations shortly after they process external script. On Linux, use auditd -a always,exit -F arch=b64 -S execve and correlate on the host process as ppid.
      • File artefacts: Sysmon EID 11 for executable files (.exe, .dll, .ps1) written by the host process shortly after a crash or script execution.

    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 ChakraCore scripting engine handles objects in memory, aka "Scripting Engine Memory Corruption Vulnerability." This affects ChakraCore. This CVE ID is unique from CVE-2018-8242, CVE-2018-8283, CVE-2018-8287, CVE-2018-8288, CVE-2018-8291, CVE-2018-8296.

    Source: NVD (NIST), OSV (Open Source Vulnerabilities), 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
    MicrosoftChakraCore
    • ChakraCore
    • —
    microsoftchakracore
    • < 1.10.1
    • 1.10.1
    nugetmicrosoft.chakracore
    • 1.7.3
    • 1.7.1
    • 1.2.0
    • 1.4.0
    • 1.2.6.62716-preview
    • 1.4.4
    • 1.4.1
    • 1.8.4
    • 1.8.1
    • 1.7.4
    • 1.5.3
    • 1.5.1
    • 1.4.3
    • 1.6.2
    • 1.4.5
    • 1.2.2
    • 1.8.3
    • 1.3.2
    • 1.5.0
    • 1.7.5
    • 1.7.2
    • 1.10.0
    • 1.3.0
    • 1.8.0
    • 1.5.2
    • 1.7.0
    • 1.6.0
    • 1.8.2
    • 1.3.1
    • 1.2.3
    • 1.2.1
    • 1.8.5
    • 1.4.2
    • 1.7.6
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    Vendors and products

    Weakness classes (CWE)

    • CWE-843Access of Resource Using Incompatible Type ('Type Confusion')

      Base

      The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.

      Entry at MITRE CWE-843

    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
    Exploit-DBEDB-ID 45217 (opens in a new tab)exploit-db.comPoC (publicly reported)reported, not verified—

    References & sources

    • NVD (NIST)vuln/detail/CVE-2018-8298advisory
    • github.comchakra-core/ChakraCore/pull/5444web
    • github.comchakra-core/ChakraCore/commit/cb9957e2763c36dbd12afa5c926146515…web
    • github.comchakra-core/ChakraCorepackage
    • portal.msrc.microsoft.comen-US/security-guidance/advisory/CVE-2018-8298web, x_refsource_CONFIRM, Patch, Vendor advisory
    • web.archive.orgweb/20210124183835/http://www.securityfocus.com/bid/104639web
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2018-8298web, government-resource, US government resource
    • exploit-db.comexploits/45217web
    • securityfocus.com104639Vulnerability database, x_refsource_BID, Broken link, Third-party advisory, Vulnerability database
    • exploit-db.com45217Exploit, x_refsource_EXPLOIT-DB, Exploit, Third-party advisory, Vulnerability database
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