CVE-2025-53945: apko Privilege Escalation Vulnerability

A critical security vulnerability, identified as CVE-2025-53945, has been discovered in apko, a tool for building and publishing OCI container images from apk packages. This flaw could potentially allow for root escalation due to incorrectly set file permissions.

🔍 TL;DR Summary

apko versions before 0.29.5 inadvertently set critical files to overly permissive permissions (0666), potentially enabling local privilege escalation to root. Users are strongly advised to upgrade to version 0.29.5, which contains a fix for this issue.

🚨 Vulnerability Details

CVE ID: CVE-2025-53945
Description: apko allows users to build and publish OCI container images built from apk packages. Starting in version 0.27.0 and prior to version 0.29.5, critical files were inadvertently set to 0666, which could likely be abused for root escalation. Version 0.29.5 contains a fix for the issue.
CVSS Score and Vector:
- Score: 7.0 (HIGH)
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L
- Explanation: This vulnerability has a high severity because while it requires local access and high attack complexity, it allows a low-privileged user to potentially escalate their privileges to root due to the changed scope. Confidentiality impact is high, while integrity and availability are lower.
Exploit Requirements: Local access to the system running a vulnerable version of apko and the ability to build OCI container images.
Affected Vendor, Product, Version:
- Vendor: chainguard-dev
- Product: apko
- Versions: 0.27.0 to 0.29.4 (inclusive)
CWE:
- CWE ID: CWE-276
- CWE Name: Incorrect Default Permissions
- Explanation: This CWE refers to scenarios where software creates files or directories with default permissions that are more permissive than intended, potentially allowing unauthorized access or modification.

📅 Timeline of Events

Version 0.27.0: Vulnerability introduced.
Version 0.29.5: Vulnerability fixed.
2025-07-18: CVE-2025-53945 assigned and vulnerability disclosed.

🧠 Exploitability & Real-World Risk

The real-world risk for CVE-2025-53945 is moderate to high. An attacker with local access to a system running a vulnerable version of apko could potentially exploit this vulnerability to gain root privileges. This could lead to complete system compromise, data theft, or denial of service.

🛠️ Recommendations

Upgrade to apko version 0.29.5 or later. This version contains the fix for the incorrect file permission issue.
Review existing container images built with vulnerable versions of apko. Rebuild these images with the updated version of apko to ensure they are not affected by this vulnerability.
Apply Principle of Least Privilege. Always ensure that file permissions are set to the minimum required level for functionality.

🧪 Technical Insight

The vulnerability arises from critical files within the apko build environment being inadvertently created with overly permissive file permissions (0666). This allows any user with access to these files to read and write to them, potentially enabling them to modify system configurations or inject malicious code to escalate their privileges.

🙌 Credit to Researcher(s)

This vulnerability was reported by GitHub Security Advisory.

🔗 References

🧵 Tags

CVE-2025-53945, apko, privilege escalation, container security, file permissions, root escalation

Summary: CVE-2025-53945 describes a privilege escalation vulnerability in apko versions prior to 0.29.5, where critical files were incorrectly assigned overly permissive file permissions (0666). This could allow a local attacker to escalate privileges to root. Users are advised to upgrade to version 0.29.5.

CVE ID: CVE-2025-53945

Risk Analysis: Successful exploitation of this vulnerability could allow an attacker to gain complete control of the system, leading to data theft, system compromise, or denial of service.

Recommendation: Upgrade to apko version 0.29.5 or later to mitigate this vulnerability. Rebuild existing container images created with vulnerable versions of apko.

Timeline

2025-07-18: CVE-2025-53945 assigned and vulnerability disclosed.

CVE-2025-53945: apko Privilege Escalation Vulnerability Due to Incorrect File Permissions