# CVE-2026-85879: Windows Subsystem for Linux TOCTOU race condition privilege escalation

Source: https://junglewise.ai/threats/cve-2026-85879-time-of-check-time-of-use-toctou-race-condition-in-windows  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-13. Updated: 2026-10-29  
License: CC BY 4.0 with a link back

CVE-2026-85879 · Severity: high · CVSS 7 · Published 2026-10-13

Windows Subsystem for Linux contains a time-of-check time-of-use race condition that allows an authorized local user to escalate their privileges on the system. An attacker with existing user access could exploit this flaw to gain elevated system permissions, potentially compromising the entire Windows machine and any data stored on it.

Technologies: [Microsoft Windows Subsystem For Linux](https://junglewise.ai/threats/technologies/windows-subsystem-for-linux). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-85879 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-85879 being exploited in the wild.

**How severe is CVE-2026-85879?** High severity, with a CVSS score of 7, published 13 October 2026.

**Which products and versions are affected?** Microsoft Windows Subsystem for Linux.

**Is there a fix for CVE-2026-85879?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-85879 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-85879?** Check whether you run Microsoft Windows Subsystem For Linux. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A TOCTOU race condition in Windows Subsystem for Linux enables privilege escalation when an authorized local attacker races between a security check and a subsequent operation. The vulnerability requires the attacker to already have user-level access to the system to exploit the window between validation and use.

## Affected products

- Microsoft Windows Subsystem for Linux

## Timeline

- 2026-10-13: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85879](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85879)

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