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MEDIUM severity

CVE-2021-42279

MEDIUM

CVE-2021-42279 is a medium-severity (CVSS 4.2) Out-of-bounds Write vulnerability in microsoft windows 10. O3 Security detects and blocks CVE-2021-42279 exploitation at runtime via eBPF exploit-chain detection and L7 egress monitoring, even on unpatched systems.

Chakra Scripting Engine Memory Corruption Vulnerability

Published
Nov 10, 2021
Updated
Jun 17, 2026
Affected
5 products
Patched
See advisory
Exploits
None indexed
Exploitation data as of Jun 17, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Description

Chakra Scripting Engine Memory Corruption Vulnerability

Affected Products

5 products · 14 configurations
OS
windows 10microsoft
6 versions
20h221h11607180919092004
OS
windows 11microsoft
all
OS
windows server 2016microsoft
2 versions
20h22004
OS
windows server 2019microsoft
all
OS
windows server 2022microsoft
all

Detection & mitigation playbook

Vendor / appliance
  1. Detect

    Inventory every microsoft windows 10 deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for remote code execution at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.

  2. Remediation status

    No patch has shipped for CVE-2021-42279 yet — track the microsoft windows 10 advisory for a fixed release and apply the workarounds below in the meantime.

  3. Mitigate without a patch

    Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.

  4. How O3 protects you

    O3 detects and blocks CVE-2021-42279 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Tailored to CVE-2021-42279. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Chakra Scripting Engine Memory Corruption Vulnerability
O3 Security · Runtime Protection

Is CVE-2021-42279 being exploited in your environment?

O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2021-42279 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.