# CVE-2026-56857: Root.Mkdir(All) can follow junctions out of the root on Windows in os

CVE-2026-56857 is fixed in 4 products on 2 platforms, first by Go Programming Language 1.27.3, released October 19, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-56857
- Priority: Urgent
- CVSS: 9.8 (Critical)
- EPSS: 0.0055
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 8, 2026
- Weakness: Insecure Operation on Windows Junction / Mount Point
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56857

## Description

On Windows, when the target of Root.Mkdir or Root.MkdirAll is a junction pointing to an empty location, the operation can create a directory at the junction target even when that target is located outside the root. This only applies to operations where the last path component is a junction (path/to/junction, but not path/junction/target).

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Windows apps | Go Programming Language | 1.27.3 | [Go Programming Language 1.27.3](https://patchblox.com/security/data/fix/windows-app/golang.go-1.27.3.md) | Oct 19, 2026 |
| Linux | go1.26 opensuse-leap 16.0 | 1.26.9-160000.1.1 | [OPENSUSE-SU-2026:22095-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22095-1.md) | Nov 7, 2026 |
| Linux | go1.26 sles 15.6 | 1.26.9-150000.1.33.1 | [SUSE-SU-2026:4629-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4629-1.md) | Nov 7, 2026 |
| Linux | go1.26 sles 15.7 | 1.26.9-150000.1.33.1 | [SUSE-SU-2026:4629-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4629-1.md) | Nov 7, 2026 |
| Linux | go1.26 sles 16.0 | 1.26.9-160000.1.1 | [SUSE-SU-2026:24239-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24239-1.md) | Nov 7, 2026 |
| Linux | go1.26-openssl sles 15.6 | 1.26.10-150600.13.18.1 | [SUSE-SU-2026:4866-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4866-1.md) | Nov 7, 2026 |
| Linux | go1.26-openssl sles 15.7 | 1.26.10-150600.13.18.1 | [SUSE-SU-2026:4866-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4866-1.md) | Nov 7, 2026 |
| Linux | go1.27 opensuse-leap 16.0 | 1.27.2-160000.1.1 | [OPENSUSE-SU-2026:22093-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22093-1.md) | Nov 7, 2026 |
| Linux | go1.27 sles 15.6 | 1.27.2-150000.1.12.1 | [SUSE-SU-2026:4625-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4625-1.md) | Nov 7, 2026 |
| Linux | go1.27 sles 15.7 | 1.27.2-150000.1.12.1 | [SUSE-SU-2026:4625-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4625-1.md) | Nov 7, 2026 |
| Linux | go1.27 sles 16.0 | 1.27.2-160000.1.1 | [SUSE-SU-2026:24237-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24237-1.md) | Nov 7, 2026 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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