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Advanced Cluster Management For KubernetesApplication · Redhat

CVE-2025-57851

MEDIUM · 6.7 CVSS v3.1 Published 2026-04-08
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
69/100
Remediation priority · Elevated
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A container privilege escalation flaw was found in certain Multicluster Engine for Kubernetes images. This issue stems from the /etc/passwd file being created with group-writable permissions during build time. In certain conditions, an attacker who can execute commands within an affected container, even as a non-root user, can leverage their membership in the root group to modify the /etc/passwd file. This could allow the attacker to add a new user with any arbitrary UID, including UID 0, leading to full root privileges within the container.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The Multicluster Engine for Kubernetes container images have /etc/passwd created with group-writable permissions (likely mode 0642) during the image build. An attacker who can execute commands in the container as a non-root user, and who has membership in the root group (gid 0), can modify /etc/passwd to add a new user with UID 0, effectively gaining root privileges within the container.

MitigationFix the container build process to ensure /etc/passwd is created with restrictive permissions (0644 or stricter) and rebuild/re-pull affected images. Consider running containers with read-only filesystems and dropping root group capabilities as defense-in-depth.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Advanced Cluster Management For KubernetesApplication
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Inspect /etc/passwd file permissions in the container
    Run 'ls -la /etc/passwd' inside the affected container or examine the container image layers to locate /etc/passwd and check its permissions
    Affected if Permissions show group-write bit set (e.g., -rw-rw-r-- or similar, where the second 'rw' indicates group-write)
  2. Identify current user and group memberships
    Run 'id' or 'groups' command inside the container to see the current user's GID and supplementary groups
    Affected if The user is a member of the root group (GID 0 appears in the group list) or has GID 0 as their primary group
  3. Test write access to /etc/passwd
    As the current user inside the container, attempt a non-destructive write test to /etc/passwd (e.g., use 'touch /etc/passwd.test' then check if group write allows modification, or attempt to append to a test copy)
    Affected if Write access is granted due to group-writable permissions and user belongs to the root group
  4. Verify container image build provenance
    If you have access to the image build process or Dockerfile, inspect how /etc/passwd is created during the image build and check the permission setting commands
    Affected if The image build process does not explicitly set /etc/passwd permissions to 644 (rw-r--r--) and the resulting image retains group-writable permissions

A user is affected if /etc/passwd has group-write permissions (the group-write bit is set) AND the user either has root group (GID 0) as a supplementary group or is the root user, allowing modification of /etc/passwd to add unauthorized UID 0 accounts.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Fix the container build process to ensure /etc/passwd is created with restrictive permissions (0644 or stricter) and rebuild/re-pull affected images. Consider running containers with read-only filesystems and dropping root group capabilities as defense-in-depth.

Fix this in Advanced Cluster Management For Kubernetes Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-57851 in production — separate from our analysis above.

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