Remote code execution via out-of-bounds write
Published Nov 10, 2021 · Updated Aug 19, 2026
Memory corruption in Microsoft Chakra Scripting Engine allows remote attackers to execute code through crafted content requiring user interaction. The engine writes outside an intended memory buffer while processing attacker-controlled script content, but Microsoft has not identified the affected function. A victim must open or render the content; successful exploitation runs code in the victim's security context, with reported confidentiality and integrity impact.
Summary
What happened
Memory corruption in Microsoft Chakra Scripting Engine allows remote attackers to execute code through crafted content requiring user interaction. The engine writes outside an intended memory buffer while processing attacker-controlled script content, but Microsoft has not identified the affected function. A victim must open or render the content; successful exploitation runs code in the victim's security context, with reported confidentiality and integrity impact.
The record
- CVE
- CVE-2021-42279
- Published
- Nov 10, 2021
- Updated
- Aug 19, 2026
- Vendor
- Microsoft
- Product
- Windows 10 Version 1507
- Classifications
- CWE-787, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Nov 10, 2021CVE publishedPublication date reported by the CVE source.
- Aug 19, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=10.0.10240.0 <10.0.10240.19119
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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