CVE-2021-32803: Arbitrary File Creation/Overwrite via insufficient symlink protection due to directory cache poisoning

highCVSS 8.2CVE-2021-32803

CSIRTS triage

vendor: npm product: npm Path traversal Code injection

What: Directory cache poisoning vulnerability allows arbitrary file creation or overwrite through insufficient symlink protection in npm package extraction.
Who is affected: Systems using npm for dependency installation with affected versions.
Urgency: High priority; allows arbitrary file overwrite with significant real-world exploitation potential.
Action: Update npm to a version with fixed symlink handling and cache management.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: high — CVSS 8.2
Published: 2026-08-06
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-32803

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Moderate exploitation riskCVE-2021-328037.8% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 94% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2021-32803	coverage & exploitation status	NVD · CVE.org

Recent advisories for Arbitrary File Creation/Overwrite

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highCVE-2021-32804: Arbitrary File Creation/Overwrite due to insufficient absolute path sanitizationmsrc · 2026-08-06
highCVE-2021-37701: Arbitrary File Creation/Overwrite via insufficient symlink protection due to directory cache p…msrc · 2026-08-06