Vulnerability · Published Aug 11, 2026 · Assigned by microsoft
CVE-2026-72971Windows Container Isolation FS Filter Driver (unionfs.sys) Tampering Vulnerability
Medium 5.5
In plain English
A medium-severity security flaw in Windows 11 version 26H1 from Microsoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities).
Severity (CVSS 3.1)5.5Medium
Exploit odds (30 days)0.4%top 69.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Improper link resolution before file access ('link following') in Windows Container Isolation FS Filter Driver (unionfs.sys) allows an authorized attacker to perform tampering locally.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Windows 11 version 26H1 | 10.0.28000.0 – before 10.0.28000.2704 |
Weakness: CWE-59 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C
References
- Windows Container Isolation FS Filter Driver (unionfs.sys) Tampering Vulnerability vendor-advisory, patch