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Security Policy

The Apptainer Technical Steering Committee (TSC) is responsible for managing the security of Apptainer, and this web page documents the security policy we follow.

Do you think you found a vulnerability?

If you believe you have discovered a vulnerability in Apptainer, please let us know. You can notify the TSC by email at

We encourage people who contact the TSC on a security matter to use email encryption. Get our PGP public key and verify the fingerprint:

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The goals of a standardized security response procedure

Before we cover the procedure that the TSC takes to mitigate newly discovered vulnerabilities, let's talk about the goals we're trying to achieve.

  • Fast turnaround: Even vulnerabilities that have not been announced publicly are a potential source of danger because a savvy hacker may be able to discover and exploit them independently. Our procedures are designed to first understand and then quickly remediate as primary goals.
  • Limited exposure: Before patches are developed and made available, our goal is to limit the spread of information until after a patch is available and key stakeholders are protected
  • Transparency: The open-source community must know exactly what the TSC intends to do about vulnerabilities and how we are are carrying out our commitment to security. Vulnerabilities are documented using the Common Vulnerabilities and Exposures (CVE) system to provide a permanent searchable record allowing administrators to accurately judge the risks of running a particular version of Apptainer within their environment.
  • Enable stakeholders over malicious actors: When a new vulnerability is publicly announced, a race begins between system administrators and those with nefarious intent. Apptainer collaborators that distribute Apptainer only in binary form are provided security patches prior to security announcements. They then distribute patched binaries to their stakeholders as a head start in the security race. Although patched binaries are made available to Apptainer stakeholders first, they are provided without releasing security-related information. This limits exposure to the open source community while still providing a way of remediation for Apptainer stakeholders, with a level of proactive measure.

Apptainer vulnerability procedure

When a vulnerability is discovered, the TSC takes the following steps:

  1. Perform due diligence to fully replicate and describe the scope and severity of the bug. (This step is expected to take hours, not days.)
  2. A CVE number is requested and embargoed until public release is made.
  3. Security patch(es) are confidentially developed. (This step is expected to take hours or days and will be carried out with appropriate urgency.)
  4. Security patches are merged into test versions of Apptainer and testing commences. Bugs related to patch(es) are fixed and testing is repeated as necessary. (This process is expected to take days.)
  5. Once patch(es) are developed and fully tested, they are pushed to a GitHub Security Advisory which keeps them hidden until ready for public disclosure.
  6. The GitHub Security Advisory is shared with Apptainer collaborators that distribute binary versions of Apptainer.
  7. The Apptainer collaborators then prepare their binaries and notify their stakeholders only with a standard notification that there is a new binary and they should upgrade. This notice will NOT contain any sensitive information and will NOT disclose the presence of a security-related patch.
  8. The stakeholders of Apptainer collaborators are given a reasonable amount of time to upgrade their installations so that when details of the exploit are revealed they are already protected.
  9. After a reasonable period of time has elapsed and stakeholders have likely upgraded (and on a Tuesday where possible as several administrators have suggested), the patches will be merged from the private development space into the public repository and a release will immediately be made. The release notes will do the following:
    1. Describe the issue in sufficient detail so that affected parties can judge whether to upgrade.
    2. If there is a mitigation or workaround detail it. If there is not, explicitly say there is no known workaround.
    3. State whether a malicious user needs access to the system to exploit the vulnerability or whether it can be exploited remotely.
    4. State which versions of Apptainer are affected and which OS-es/kernels are affected.
    5. Reference relevant CVE number(s).
  10. At the same time that a release is being made, the CVE(s) will be filled out with all relevant information and released from embargo.
  11. Announcements will be made on Slack and on the Google Group that a new version of Apptainer is available with all relevant security information and links to release notes.