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PYSEC-2019-109

CVE-2019-12760GHSA-22mf-97vh-x8rw

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (parso 0.5.0), 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

  • PyPI parso

    Affected
    < 0.5.0
    Fixed in
    0.5.0

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
not scored
EPSS
  • CVE-2019-12760: 1.53% estimated exploitation activity in the next 30 days; percentile 74.85 (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.

DISPUTED A deserialization vulnerability exists in the way parso through 0.4.0 handles grammar parsing from the cache. Cache loading relies on pickle and, provided that an evil pickle can be written to a cache grammar file and that its parsing can be triggered, this flaw leads to Arbitrary Code Execution. NOTE: This is disputed because "the cache directory is not under control of the attacker in any common configuration."

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

    Published from osv record PYSEC-2019-109

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-2019-12760

Advisory: PYSEC-2019-109
IDs: CVE-2019-12760, GHSA-22mf-97vh-x8rw
Record: https://patchnext.com/advisories/cve-2019-12760 (revision 1, source checked 24 Oct 2026, 04:13 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: parso 0.5.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI parso: affected < 0.5.0; fixed in 0.5.0

## Suggested inspection (read-only)
- `python -m pip show parso`: 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 parso.
- 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/PYSEC-2019-109 (OSV record PYSEC-2019-109 lists affected ranges: PyPI parso >=0 <0.5.0 (fixed))

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