CVE-2021-37701: Arbitrary File Creation/Overwrite via insufficient symlink protection due to directory cache poisoning using symbolic links

CSIRTS triage

What

Arbitrary file creation or overwrite vulnerability via insufficient symlink protection and directory cache poisoning.

Who is affected

Systems with shared directory structures and symlink-following code; local attackers can exploit.

Urgency

High severity (CVSS 8.2); not exploited but straightforward exploitation path for local privilege escalation.

Action

Identify affected application, apply symlink protection patches, and implement proper directory cache handling.

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

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-2021-37701

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-2021-377013.3% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 87% of all EPSS-scored CVEs.

Referenced CVEs

More from Microsoft Security Response Center

• highCVE-2026-70130: Microsoft Office Remote Code Execution Vulnerability2026-08-11
• highCVE-2026-70354: .NET Core Remote Code Execution Vulnerability2026-08-11
• highCVE-2026-68792: Microsoft Office Elevation of Privilege Vulnerability2026-08-11
• highCVE-2026-66807: Microsoft Office Graphics Component Remote Code Execution Vulnerability2026-08-11
• highCVE-2026-64909: Microsoft Office Remote Code Execution Vulnerability2026-08-11