CVE-2026-72971
MEDIUM 5.5 ALL-YEARSImproper link resolution before file access ('link following') in Windows Container Isolation FS Filter Driver (unionfs.sys) allows an authorized attacker to perform tampering locally.
No known exploitation, public exploit, or elevated probability at this time. Track for changes.
Exploitation likelihood
0.4%chance of exploitation in 30 days · 30th percentile
Impact if exploited
5.5CVSS 3.1 · MEDIUM · CNA
- ConfidentialityNone
- IntegrityHigh
- AvailabilityNone
What an attacker needs
- ⚠Access: Requires local access to the host
- ⚠Privileges: Requires a low-privilege account
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept
No public PoC is currently catalogued.
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Tracked sources are checked weekly for the full archive, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.
Weakness (CWE)
- CWE-59: : Improper Link Resolution Before File Access ('Link Following')
CVSS 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 and research data (JSON)
Known Affected Software Configurations
| Vendor | Product | Version range |
|---|---|---|
| Microsoft | Windows 11 26h1 | < 10.0.28000.2704 |
| Microsoft | Windows 11 26h1 | < 10.0.28000.2704 |
All CVSS metrics
- MEDIUM 5.5 v3.1 · CNA Primary
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 - MEDIUM 5.5 v3.1 · NVD Secondary
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
References
Patches & mitigations
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-72971 CVE record · microsoft · Updated 2026-10-21T20:53:10.809Z
NVD · CVE-2026-72971 · Updated 2026-10-24T15:10:00.190
Advisories
- https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-56603 EUVD · EUVD-2026-56603
Sources: NVD · CVE.org · All sources and attribution · EPSS