Executive Summary

CVE-2026-41013 is a high-severity vulnerability in Cloud Foundry's SMB volume mount handling within the diego-release component. It allows low-privileged Cloud Foundry space developers to bypass input validation by exploiting a comma smuggling technique, which lets them inject arbitrary CIFS mount options.

This bypass circumvents the intended allowlist designed to restrict dangerous mount operations on shared Diego infrastructure. As a result, attackers can manipulate mount options to weaken security settings, alter credentials, override security protocols, or apply other forbidden configurations.

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Impact Analysis

Exploiting this vulnerability can lead to privilege escalation, unauthorized filesystem access, and compromise of the multi-tenant security model on Diego cells.

• Attackers can weaken security by enabling dangerous mount options such as setuids, noperm, and nounix.
• They can alter credentials used for mounting by specifying custom credential paths or user IDs.
• Security protocols can be overridden, potentially bypassing authentication or encryption mechanisms.

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Detection Guidance

Detection of this vulnerability involves auditing existing SMB volume mounts on Diego cells to identify any mounts with suspicious or unauthorized CIFS mount options that bypass the allowlist.

Look for mount options that include potentially dangerous flags such as setuids, noperm, nounix, or options that override credentials or security protocols like cruid=, credentials=, or sec=.

Commands to help detect such mounts could include inspecting mounted filesystems on Diego cells using standard Linux commands such as:

• mount | grep cifs
• cat /proc/mounts | grep cifs

Review the output for any mount options that are not part of the allowed list or that include suspicious parameters indicating an injection of arbitrary CIFS mount options.

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Mitigation Strategies

Immediate mitigation steps include upgrading affected components to fixed versions: smb-volume-release to v3.60.0 or later, and CF Deployment to v56.0.0 or later.

If upgrading is not immediately possible, apply workarounds such as:

• Disabling SMB volume mounting for space developers to prevent exploitation.
• Restricting SMB operations to platform operators only.
• Auditing existing SMB mounts for suspicious or unauthorized mount options.
• Implementing network-level controls around Diego cells to limit exposure.

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Compliance Impact

This vulnerability enables low-privileged developers to bypass security controls and escalate privileges on multi-tenant Diego cells by injecting arbitrary CIFS mount options. Such unauthorized access and privilege escalation can lead to compromise of data confidentiality and integrity.

As a result, organizations using affected versions may face increased risk of unauthorized data access or modification, which could impact compliance with data protection regulations like GDPR and HIPAA that require strict access controls and protection of sensitive information.

Mitigating this vulnerability by upgrading or applying recommended workarounds is essential to maintain compliance with these standards.

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