Compliance Impact

The vulnerability allows a malicious container image to create directories or modify ownership on the host filesystem, potentially leading to unauthorized modification of host filesystem integrity.

While the confidentiality and availability impacts are minimal, the integrity impact could affect compliance with standards and regulations that require strict control over data integrity and system security, such as GDPR and HIPAA.

Unauthorized modification of filesystem ownership or structure could lead to violations of data protection and security requirements mandated by these regulations.

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Executive Summary

CVE-2026-55686 is a symlink traversal vulnerability in Podman affecting the WORKDIR functionality in container images. A malicious container image with a WORKDIR path containing a symlink can create directories or modify file ownership on the host filesystem.

While creating directories is straightforward, modifying ownership requires a race condition involving an untrusted process manipulating the host filesystem during path dereferencing.

This vulnerability affects Podman versions from 3.0.0 up to 5.7.0 and was fixed in version 5.7.1.

Exploitation involves crafting container images with carefully constructed symlinks in the WORKDIR path, which can lead to unintended filesystem changes on the host.

The severity is rated as Moderate with a CVSS score of 5.3, indicating low attack complexity and no required privileges or user interaction.

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Impact Analysis

This vulnerability can allow a malicious container image to create directories or modify ownership of files on the host filesystem, potentially compromising the integrity of the host system.

Although confidentiality and availability impacts are minimal, unauthorized modification of the host filesystem could lead to security risks such as privilege escalation or unauthorized access to host resources.

The attack does not require any privileges or user interaction, making it easier for an attacker to exploit if they can run malicious container images.

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Detection Guidance

This vulnerability can be detected by checking if your Podman installation is a vulnerable version (from 3.0.0 up to 5.7.0) and by testing whether malicious container images with symlinked WORKDIR paths can create directories or modify ownership on the host filesystem.

Two proof-of-concept scripts named test1.bash and test2.bash demonstrate the vulnerability by creating a directory at /var/BREAKOUT on the host, even when the container's working directory is set differently.

To detect exploitation attempts or test your system, you can run these proof-of-concept scripts if available, or manually inspect container images for symlinks in the WORKDIR path.

Additionally, monitoring your host filesystem for unexpected directory creation or ownership changes, especially at paths like /var/BREAKOUT, can help detect exploitation.

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Mitigation Strategies

The immediate mitigation step is to upgrade Podman to version 5.7.1 or later, where this vulnerability has been fixed.

Until the upgrade is applied, avoid running untrusted or malicious container images that may contain symlinks in the WORKDIR path.

You can also monitor and restrict container image sources and implement host filesystem monitoring to detect unauthorized directory creation or ownership changes.

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