CVE-2026-56857Root.Mkdir(All) can follow junctions out of the root on Windows in os
Updated under an hour ago ()
Does this affect you?
It affects Go standard library os and 1 other product. Add what you run to find out whether that includes you.
EPSS puts the chance of exploitation in the next 30 days at 0.49%, higher than 41% of scored CVEs.
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Free account, 1 product
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).
- CVSS
- 9.8 CRITICAL (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- CWE-1386
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- 0.49% (percentile 41)
- Assigned by
- Go
- NVD analysis
- Awaiting Analysis
- Record last updated
- Oct 9, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Go standard library os go_standard_library:os (from the name) | before 1.26.9; from 1.27.0-0 before 1.27.2 | CNA record |
Go standard library internal/syscall/windows go_standard_library:internal_syscall_windows (from the name) | before 1.26.9; from 1.27.0-0 before 1.27.2 | CNA record |
References
- https://go.dev/cl/847305
- https://go.dev/issue/81739
- https://groups.google.com/g/golang-announce/c/U2fTuyDJznI
- https://pkg.go.dev/vuln/GO-2026-6604
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.