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.NET
.NET NuGet
Not in CISA KEV
HIGH severity

CVE-2021-42279 — Microsoft.ChakraCore

HIGH

CVE-2021-42279 is a high-severity (CVSS 7.5) Out-of-bounds Write vulnerability in Microsoft.ChakraCore. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

Chakra Scripting Engine and ChakraCore Vulnerable to Memory Corruption

Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
None indexed
Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
2.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs84th percentile — riskier than 84% of all scored CVEsHighest risk
1.45%2.12%2.79%3.45%3.0%2.3%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
.NETMicrosoft.ChakraCore

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.

Description

Chakra Scripting Engine and ChakraCore are vulnerable to memory corruption due to an out-of-bounds write. The Microsoft advisory for CVE-2021-42279 was modified in August 2022 to include Microsoft.ChakraCore as an affected product.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
.NETNuGetMicrosoft.ChakraCoreall versionsNo fix

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

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.ChakraCore, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    The records we use list no patched version of Microsoft.ChakraCore for CVE-2021-42279. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

  3. Mitigate without a patch

    Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.

Frequently Asked Questions

Chakra Scripting Engine and ChakraCore are vulnerable to memory corruption due to an out-of-bounds write. The Microsoft advisory for CVE-2021-42279 was modified in August 2022 to include Microsoft.ChakraCore as an affected product.
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CVE-2021-42279: Microsoft Memory Corruption (High 7.5)