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Full vulnerability report · 2021
CVE-2021-42279High confidence

Chakra Scripting Engine Memory Corruption Vulnerability

Microsoft · ChakraCore

4.2MediumCVSS 3.1
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 2.30% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Microsoft ChakraCore and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: As exposure requiresRemediation target: Within 365 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Open-source package ranges1 source-attributed range

These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.

Ecosystem and packageAffected rangeFirst fixed versionEvidence
NuGetMicrosoft.ChakraCoreECOSYSTEM: introduced 0; last affected 1.11.24Not statedOSV record ↗aggregator derived · 8 Nov 2023
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2022-4364

No EUVD known-exploited evidence

Chakra Scripting Engine Memory Corruption Vulnerability

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
4.2 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
01

What, why and how

Chakra Scripting Engine Memory Corruption Vulnerability

What

Chakra Scripting Engine Memory Corruption Vulnerability

Why

A bounds error lets data be written beyond the intended memory region, potentially corrupting control data.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Chakra Scripting Engine Memory Corruption Vulnerability

Why

A bounds error lets data be written beyond the intended memory region, potentially corrupting control data.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Out-of-bounds Write → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
Required interaction required
Attack complexity
High: exploitation depends on specific conditions
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-787 ↗

CWE-787: Out-of-bounds Write. The product writes data past the end, or before the beginning, of the intended buffer.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N/E:P/RL:O/RC:C

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CLowConfidentiality impact: A successful attack can cause a limited loss.ILowIntegrity impact: A successful attack can cause a limited loss.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-787
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2022-4364Official EUVD mapping

Chakra Scripting Engine Memory Corruption Vulnerability

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20211117Security Bulletin 17 Nov 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 17 Nov 2021, published on 17 November 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-862Multiples vulnérabilités dans Microsoft Windows

d?id=CVE-2021-41371 Référence CVE CVE-2021-41377 https://www.cve.org/CVERecord?id=CVE-2021-41377 Référence CVE CVE-2021-41378 https://www.cve.org/CVERecord?id=CVE-2021-41378 Référence CVE CVE-2021-41379 https://www.cve.org/CVERecord?id=CVE-2021-41379 Référence CVE CVE-2021-42274 https://www.cve.org/CVERecord?id=CVE-2021-42274 Référence CVE CVE-2021-42275 https://www.cve.org/CVERecord?id=CVE-2021-42275 Référence CVE CVE-2021-42276 https://www.cve.org/CVERecord?id=CVE-2021-42276 Référence CVE CVE-2021-42277 https://www.cve.org/CVERecord?id=CVE-2021-42277 Référence CVE CVE-2021-42278 https://www.cve.org/CVERecord?id=CVE-2021-42278 Référence CVE CVE-2021-42279 https://www.cve.org/CVERecord?id=CVE-2021-42279 Référence CVE CVE-2021-42280 https://www.cve.org/CVERecord?id=CVE-2021-42280 Référence CVE CVE-2021-42282 https://www.cve.org/CVERecord?id=CVE-2021-42282 Référence CVE CVE-2021-42283 https://www.cve.org/CVERecord?id=CVE-2021-42283 Référence CVE CVE-2021-42284 https://www.cve.org/CVERecord?id=CVE-2021-42284 Référence CVE CVE-2021-42285 https://www.cve.org/CVERecord?id=CVE-2021-42285 Référence CVE CVE-2021-42286 https://www.cve.org/CVERecord?id=CVE-2021-42286 Référence CVE CVE-2021-42287 https://www.cve.org/CVERecord?id=CVE-2021-42287 Référence CVE CVE-2021-42288 https://www.cve.org/CVERecord?id=

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-004144複数の Microsoft Windows 製品におけるメモリ破損の脆弱性

Microsoft Windows 10、Windows 11、Windows Server には、Chakra スクリプトエンジンに不備があるため、メモリ破損の脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5435MS 11월 보안 위협에 따른 정기 보안 업데이트 권고

dows 피드백 허브 권한 상승 취약성 Windows Hello CVE-2021-42288 Windows Hello 보안 기능 우회 취약성 Windows Installer CVE-2021-41379 Windows Installer 권한 상승 취약성 Windows Kernel CVE-2021-42285 Windows 커널 권한 상승 취약성 Windows NTFS CVE-2021-42283 NTFS 권한 상승 취약성 Windows NTFS CVE-2021-41378 Windows NTFS Remote Code Execution Vulnerability Windows NTFS CVE-2021-41370 NTFS 권한 상승 취약성 Windows NTFS CVE-2021-41367 NTFS 권한 상승 취약성 Windows RDP CVE-2021-41371 Windows RDP(원격 데스크톱 프로토콜) 정보 유출 취약성 Windows RDP CVE-2021-38666 원격 데스크톱 클라이언트 원격 코드 실행 취약성 Windows RDP CVE-2021-38665 원격 데스크톱 프로토콜 클라이언트 정보 유출 취약성 Windows RDP CVE-2021-38631 Windows RDP(원격 데스크톱 프로토콜) 정보 유출 취약성 Windows Scripting CVE-2021-42279 Chakra 스크립팅 엔진 메모리 손상 취약성 Windows Virtual Machine Bus CVE-2021-26443 Microsoft Virtual Machine Bus (VMBus) Remote Code Execution Vulnerability ##### □ 작성 : 침해사고분석단 취약점분석팀

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 10 Nov 2021 · Last source change 19 Aug 2026, 16:27 UTC · CWE-787 · Out-of-bounds Write

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2022-4364
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceNIST NVD
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed: added remediation: portal.msrc.microsoft.com/CVE-2021-42279; removed patch: msrc.microsoft.com/CVE-2021-42279; removed remediation: msrc.microsoft.com/CVE-2021-42279.
    Before
    patch: msrc.microsoft.com/CVE-2021-42279 · patch: portal.msrc.microsoft.com/CVE-2021-42279 · remediation: msrc.microsoft.com/CVE-2021-42279
    After
    patch: portal.msrc.microsoft.com/CVE-2021-42279 · remediation: portal.msrc.microsoft.com/CVE-2021-42279
    portal.msrc.microsoft.com ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added patch: msrc.microsoft.com/CVE-2021-42279; added remediation: msrc.microsoft.com/CVE-2021-42279; removed remediation: portal.msrc.microsoft.com/CVE-2021-42279.
    Before
    patch: portal.msrc.microsoft.com/CVE-2021-42279 · remediation: portal.msrc.microsoft.com/CVE-2021-42279
    After
    patch: msrc.microsoft.com/CVE-2021-42279 · patch: portal.msrc.microsoft.com/CVE-2021-42279 · remediation: msrc.microsoft.com/CVE-2021-42279
    msrc.microsoft.com ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    N/A; 10.0.0 < 10.0.19043.1348; 10.0.0 < 10.0.22000.318; 10.0.0 < 10.0.20348.350; 10.0.0 < 10.0.19042.1348; 10.0.0 < 10.0.18363.1916; 10.0.0 < 10.0.19041.1348 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    -; 10.0.10240.0 < 10.0.10240.19119; 10.0.14393.0 < 10.0.14393.4770; 10.0.0 < 10.0.17763.2300; 10.0.17763.0 < 10.0.17763.2300; 10.0.0 < 10.0.18363.1916; 10.0.0 < 10.0.19041.1348; 10.0.0 < 10.0.19042.1348 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2022-4364↗Patch or update reference↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2021-42279 · cve.blacktree.nl