Security Advisory: Compromise of PyTorch Lightning PyPI Package Versions

Published: 2026-04-30
Last Updated: 2026-05-12

Github Advisory: CVE-2026-44484

We have identified a security incident affecting certain versions of one of our PyPI packages.

What happened

We have determined that one or more released versions of this package have been compromised and include malicious code.

Our current investigation indicates that the affected versions have introduced functionality consistent with a credential harvesting mechanism. We are still actively analysing the scope and behaviour of the code.

At this stage, the root cause of the compromise is still under investigation.

What versions are affected

We are currently working to confirm the exact set of impacted versions.

We have determined the following versions as affected and ask that you delete them from your systems:

• 2.6.2
• 2.6.3

We will update this advisory if the versions impacted by this vulnerability change.

What you should do immediately

If you have installed or are running any potentially affected versions:

• Assume the environment may be compromised
• Immediately rotate all credentials and secrets that may have been exposed, including:
  • API keys
  • Access tokens
  • SSH keys
  • Service account credentials
• Rebuild affected systems from a known clean state
• Pin PyTorch Lightning to version 2.6.1
• Review logs for any suspicious or unauthorised activity

Actions we have taken

• Quarantined malicious versions from PyPI
• Recommend using version 2.6.1: https://github.com/Lightning-AI/pytorch-lightning/releases/tag/2.6.1
• Revoked and rotated all internal credentials associated with our release process
• Initiated a full investigation into the compromise

Ongoing investigation

We are actively working to:

• Identify the exact mechanism of compromise
• Confirm the full set of affected versions
• Determine the behaviour and impact of the malicious code