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High, CVSS 7.1amended

Picklescan (scan_pytorch) Bypass via dynamic eval MAGIC_NUMBER

CVE-2026-53875GHSA-97f8-7cmv-76j2

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (picklescan 1.0.3), 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
7.1 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-53875: 0.55% estimated exploitation activity in the next 30 days; percentile 46.15 (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.

Summary This is a scanning bypass to scanpytorch function in picklescan. As we can see in the implementation of getmagicnumber() that uses pickletools.genops(data) to get the magicnumber with the condition opcode.name includes INT or LONG, but the PyTorch's implemtation simply uses picklemodule.load() to get this magicnumber. For this implementation difference, we then can embed the magiccode into the PyTorch file via dynamic eval on the \\reduce\\ trick, which can make the pickletools.genops(data) cannot get the magiccode in INT or LONG type, but the picklemodule.load() can still return the same magiccode, eading to a bypass. PoC Attack Step 1 we can edit the source code of the function \legacy\save() as follows: Attack Step 2 with the modified version of PyTorch, we run the following PoC to generate the payload.pt: Picklescan result Victim Step then you can find the illegal file /tmp/hacked created in your local system. Impact Craft malicious PyTorch payloads to bypass picklescan,…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-97f8-7cmv-76j2

  2. Revision 2 · amended ·

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

  3. Revision 1 · created ·

    Published from osv record GHSA-97f8-7cmv-76j2

Agent brief

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# Patch Next advisory brief: CVE-2026-53875

Advisory: Picklescan (scan_pytorch) Bypass via dynamic eval MAGIC_NUMBER
IDs: CVE-2026-53875, GHSA-97f8-7cmv-76j2
Record: https://patchnext.com/advisories/cve-2026-53875 (revision 3, source checked 26 Oct 2026, 13:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: picklescan 1.0.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI picklescan: affected < 1.0.3; fixed in 1.0.3

## Suggested inspection (read-only)
- `python -m pip show picklescan`: 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 picklescan.
- 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-97f8-7cmv-76j2 (OSV record GHSA-97f8-7cmv-76j2 lists affected ranges: PyPI picklescan >=0 <1.0.3 (fixed))
- Verified: https://github.com/advisories/GHSA-97f8-7cmv-76j2 (GitHub-reviewed advisory GHSA-97f8-7cmv-76j2 lists affected ranges: PyPI picklescan >=0 <1.0.3)

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