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Medium, CVSS 5.3amended

Zip Flag Bit Exploit Crashes Picklescan But Not PyTorch

CVE-2025-1945GHSA-w8jq-xcqf-f792

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (picklescan 0.0.23), 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
5.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2025-1945: 0.55% estimated exploitation activity in the next 30 days; percentile 46.31 (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 PickleScan fails to detect malicious pickle files inside PyTorch model archives when certain ZIP file flag bits are modified. By flipping specific bits in the ZIP file headers, an attacker can embed malicious pickle files that remain undetected by PickleScan while still being successfully loaded by PyTorch's torch.load(). This can lead to arbitrary code execution when loading a compromised model. Details PickleScan relies on Python’s zipfile module to extract and scan files within ZIP-based model archives. However, certain flag bits in ZIP headers affect how files are interpreted, and some of these bits cause PickleScan to fail while leaving PyTorch’s loading mechanism unaffected. By modifying the flagbits field in the ZIP file entry, an attacker can: - Embed a malicious pickle file (badfile.pkl) in a PyTorch model archive. - Flip specific bits (e.g., 0x1, 0x20, 0x40) in the ZIP metadata. - Prevent PickleScan from scanning the archive due to errors raised by zipfile. -…

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

    Amended from ghsa record GHSA-w8jq-xcqf-f792

  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-w8jq-xcqf-f792

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2025-1945

Advisory: Zip Flag Bit Exploit Crashes Picklescan But Not PyTorch
IDs: CVE-2025-1945, GHSA-w8jq-xcqf-f792
Record: https://patchnext.com/advisories/cve-2025-1945 (revision 3, source checked 26 Oct 2026, 13:35 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: picklescan 0.0.23. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI picklescan: affected < 0.0.23; fixed in 0.0.23

## 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-w8jq-xcqf-f792 (OSV record GHSA-w8jq-xcqf-f792 lists affected ranges: PyPI picklescan >=0 <0.0.23 (fixed))
- Verified: https://github.com/advisories/GHSA-w8jq-xcqf-f792 (GitHub-reviewed advisory GHSA-w8jq-xcqf-f792 lists affected ranges: PyPI picklescan >=0 <0.0.23)

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