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Vulnerabilities

Vulnerability · CVE-2026-56857

Root.Mkdir(All) can follow junctions out of the root on Windows in os

Published Oct 8, 2026 · catalog updated Oct 16, 2026 · Root.Mkdir(All) can follow junctions

Check if you run it

No confirmed exploitation is on record for CVE-2026-56857. EPSS is 0.49%. Act only if a listed version of Root.Mkdir(All) can follow junctions is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Root.Mkdir(All) can follow junctions).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Unknown—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.49%
Remediation
Not established
Affected products
Go stdlib

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).

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Go stdlib0 → 1.26.9

How to fix CVE-2026-56857

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-56857. EPSS is 0.49%. Act only if a listed version of Root.Mkdir(All) can follow junctions is installed.

Which versions are affected?

Compare what you have installed with 0 → 1.26.9. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.49%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Windows security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 8, 2026 · Go Vulnerability Database

    Detected

    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).

  2. Oct 16, 2026 · Go Vulnerability Database

    Fix available

    stdlib fixed in 1.26.9

  3. Oct 16, 2026 · Go Vulnerability Database

    Fix available

    stdlib fixed in 1.26.9

  4. Oct 16, 2026 · Go Vulnerability Database

    Updated

    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).

Sources

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.