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High, CVSS 8.4amended

PyTorch Lightning allows arbitrary code execution through checkpoint _instantiator hyperparameters

CVE-2026-58659GHSA-qqmf-gpg7-g8gw

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (pytorch-lightning 2.6.6; lightning 2.6.6), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.4 · CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-58659: 0.63% estimated exploitation activity in the next 30 days; percentile 50.07 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

PyTorch Lightning through 2.6.5, fixed in commit d710d68, contains a remote code execution vulnerability in the loadstate function that imports and executes attacker-controlled module names from checkpoint instantiator hyperparameters. Attackers can craft malicious checkpoint files that bypass weightsonly=True protections to execute arbitrary code when LightningModule.loadfromcheckpoint is called.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-qqmf-gpg7-g8gw

  2. Revision 3 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 2 · amended ·

    Amended from osv record PYSEC-2026-3967

  4. Revision 1 · created ·

    Published from osv record GHSA-qqmf-gpg7-g8gw

Agent brief

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# Patch Next advisory brief: CVE-2026-58659

Advisory: PyTorch Lightning allows arbitrary code execution through checkpoint _instantiator hyperparameters
IDs: CVE-2026-58659, GHSA-qqmf-gpg7-g8gw
Record: https://patchnext.com/advisories/cve-2026-58659 (revision 4, source checked 26 Oct 2026, 13:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pytorch-lightning 2.6.6; lightning 2.6.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI pytorch-lightning: affected < 2.6.6; fixed in 2.6.6
- PyPI lightning: affected < 2.6.6; fixed in 2.6.6

## Suggested inspection (read-only)
- `python -m pip show pytorch-lightning`: prints the installed version. Run with the environment that serves production active.
- `python -m pip show lightning`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pytorch-lightning, lightning.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-qqmf-gpg7-g8gw (OSV record GHSA-qqmf-gpg7-g8gw lists affected ranges: PyPI lightning >=0 <2.6.6 (fixed))
- Verified: https://osv.dev/vulnerability/PYSEC-2026-3967 (OSV record PYSEC-2026-3967 lists affected ranges: PyPI pytorch-lightning >=0 <2.6.6 (fixed))
- Verified: https://github.com/advisories/GHSA-qqmf-gpg7-g8gw (GitHub-reviewed advisory GHSA-qqmf-gpg7-g8gw lists affected ranges: PyPI lightning >=0 <2.6.6)

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