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Critical 2 vendors · 2 advisories

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

CVE-2026-56857 key facts

CISA KEV
Not listed (catalogue checked )
Highest advisory rating
Critical
CVSS base score
3.3 (Red Hat)
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H · base score 9.8, scored by CISA-ADPAttack vector: network. Attack complexity: low. Privileges required: none. User interaction: none. Scope: unchanged. Confidentiality impact: high. Integrity impact: high. Availability impact: high.
Weakness
  • CWE-1386: Insecure Operation on Windows Junction / Mount Point
EPSS
0.55% chance of exploitation in the next 30 days (46th percentile). FIRST EPSS, .
CISA SSVC
Exploitation: none observed. Automatable: yes. Technical impact: total. CISA, .
Vendor advisories
2 from Red Hat, Veeam
Assigned by
Go (CNA)
CVE record published
Listed by VulniPulse
Record changed

Ratings, versions and fixes are quoted from the vendor advisories that cover only CVE-2026-56857; each belongs to its advisory, not to every product listed. How records are collected and checked.

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).

Text from the CVE.org record (Go).

Vendor advisories for CVE-2026-56857

Red Hat

1 advisory
  • Advisory severityLow3.3

    Low [CVE-2026-56857] Directory traversal via Windows junction handling

    CVE-2026-56857Source published Source updated

    Directory traversal via Windows junction handling. Red Hat rates this low (CVSS 3.3). Weakness: CWE-59. Affected products named by the advisory: OpenShift Developer Tools and Services; OpenShift Pipelines; OpenShift Serverless; OpenShift Service Mesh 3; and 32 more.

    Related products — impact not confirmed
    • OpenShift Developer Tools and Services
    • OpenShift Pipelines
    • OpenShift Serverless
    • OpenShift Service Mesh 3

    32 more entries in the full advisory.

    Source-reported affected versions
    Affected-version details not available in this record.
    Source-reported fixed versions
    No fixed-version detail extracted. This does not mean no fix exists.
    Mitigation guidance
    No mitigation guidance extracted; consult the source.
    Full advisory and evidenceOpen source bulletin

Veeam

1 advisory
  • Advisory severityCritical

    Critical [CVE-2020-14040 +110] List of Security Fixes and Improvements in Veeam Kasten for Kubernetes

    KB4825Source published

    This bulletin covers 111 CVEs. The products, versions, score and guidance below describe the bulletin; check its source for applicability to this specific CVE.

    List of Security Fixes and Improvements in Veeam Kasten for Kubernetes KB ID: 4825 Product: Kasten K10 by Veeam | 3 | 5 | 5.5 | 6 | 6.5 Published: 2026-03-02 Last Modified: Purpose This article aims to provide our customers' security and compliance teams with detailed information on security improvements. - Veeam Kasten for Kubernetes — Release Notes - Also resolves 13 Medium and 7 Low severity CVEs in the same and other packages. - Upgraded the frontend's bundled JavaScript dependencies to resolve GHSA-g2v6-rqmx-r4w6 in @vue/server-renderer (High). - Upgraded to latest UBI base image to resolve multiple CVEs in base OS packages. - Updated the Go runtime to resolve additional upstream Go CVEs. - Updated the bundled Prometheus Helm chart to resolve security issues. - Upgraded the…

    Related products — impact not confirmed
    No product details extracted. Check the source bulletin.
    Source-reported affected versions
    Affected-version details not available in this record.
    Source-reported fixed versions
    • 8.5.10
    • 8.5.5
    • 1.26.1
    • 8.5.3

    20 more entries in the full advisory.

    Mitigation guidance
    • List of Security Fixes and Improvements in Veeam Kasten for Kubernetes KB ID: 4825 Product: Veeam Kasten for Kubernetes | 7 | 7.5 | 8 | 8.5 | 9 Kasten K10 by Veeam | 3 | 5 | 5.5 | 6 | 6.5 Published: 2026-03-02 Last Modified: 2026-11-05 Purpose This article describes all security-related fixes and improvements introduced in each release or update of Veeam Kasten for Kubernetes.
    • It is recommended to upgrade Veeam Kasten and to refresh the token by manually logging out.
    • Mitigation: Configure a bucket-level Default Object Lock retention so the object store stamps new objects at write time, or upgrade to Kasten 8.5.10.
    • Veeam Kasten for Kubernetes 8.5.5 Upgrade to Go 1.26.1 to address CVE-2026-25679 and CVE-2026-27142 Updated the UBI base image to address CVE-2026-4111 Veeam Kasten for Kubernetes 8.5.3 Upgrade to Go 1.25.7 to address CVE-2025-61732.

    4 more entries in the full advisory.

    Workarounds
    • Veeam Kasten for Kubernetes 8.0.14 Improved logging security for specific block mode datamover upload Pod invocations.
    Full advisory and evidenceOpen source bulletin

References

Timeline

  1. First vendor advisory listed by VulniPulse
  2. CVE record published
  3. CVE record last updated

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