GHSA-22qq-2fwx-7p67: Pip/pylint vulnerability

Q: Who is realistically exposed to this issue?

Users running pylint on multi-user hosts are exposed if another user can write to pylint's cache directory. An attacker does not need access to the pylint configuration or the code being linted.

Q: What does an attacker need to exploit it?

The attacker needs write access to the directory used by PYLINT_HOME so they can place a crafted pickle in pylint's statistics cache. Code executes when pylint later reloads that cache with pickle.load.

Q: Is the default configuration affected?

The default PYLINT_HOME location is ~/.cache/pylint, which is writable only by the user running pylint. It is not exposed to this cross-user attack unless its permissions or location have been changed to allow untrusted writers.

Q: What can be done before upgrading?

Do not configure PYLINT_HOME to use an untrusted, shared, or group-writable directory. Ensure the cache directory is writable only by the user that runs pylint.

Q: What version fixes the issue?

Pylint 4.0.9 and later store the result cache as JSON rather than pickle, preventing this cache-based code execution.

Published Oct 27, 2026

Updated

Impact

Since 2006 / pylint 0.15.2, pylint caches its stats as pickles in PYLINTHOME and reload them on the next run with pickle.load. Someone without access to the configuration or linted code, but with access to the cache directory (predictable PYLINTHOME on a multi-user host) can write a crafted pickle that will runs arbitrary code when pylint access its stat cache.

Patches

From pylint 4.0.9, the result cache is now stored as JSON instead of pickle, preventing code-execution.

Workarounds

Until upgrading do not point PYLINTHOME to an untrusted, shared, or group-writable directory. The default value, ~/.cache/pylint, is writable only by the user running pylint.

Credits

- Reported privately via Tidelift coordinated disclosure (Dan Lenz).

Affected Software

1 affected componentFixes available

pip/pylint<4.0.9

4.0.9

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade pip/pylint to a version that resolves this vulnerability.
Fixed in 4.0.9
Upgrade
Upgrade pylint to a version that resolves this vulnerability.
Fixed in 4.0.9
Configuration
Do not point PYLINT_HOME to an untrusted, shared, or group-writable directory; use a directory writable only by the user running pylint.
pylint PYLINT_HOME = a user-only writable directory

Event History

Oct 27, 2026

Advisory Published

via GitHub·02:46 PM

Data Sourced

via GitHub·02:46 PM

DescriptionWeaknessAffected Software

Frequently Asked Questions

Who is realistically exposed to this issue?

Users running pylint on multi-user hosts are exposed if another user can write to pylint's cache directory. An attacker does not need access to the pylint configuration or the code being linted.

What does an attacker need to exploit it?

The attacker needs write access to the directory used by PYLINT_HOME so they can place a crafted pickle in pylint's statistics cache. Code executes when pylint later reloads that cache with pickle.load.

Is the default configuration affected?

The default PYLINT_HOME location is ~/.cache/pylint, which is writable only by the user running pylint. It is not exposed to this cross-user attack unless its permissions or location have been changed to allow untrusted writers.

What can be done before upgrading?

Do not configure PYLINT_HOME to use an untrusted, shared, or group-writable directory. Ensure the cache directory is writable only by the user that runs pylint.

What version fixes the issue?

Pylint 4.0.9 and later store the result cache as JSON rather than pickle, preventing this cache-based code execution.

GHSA-22qq-2fwx-7p67: Pip/pylint vulnerability

Affected Software

Remediation

Event History

Frequently Asked Questions

Who is realistically exposed to this issue?

What does an attacker need to exploit it?

Is the default configuration affected?

What can be done before upgrading?

What version fixes the issue?

Company

Resources

Contact

Frequently Asked Questions

Who is realistically exposed to this issue?

What does an attacker need to exploit it?

Is the default configuration affected?

What can be done before upgrading?

What version fixes the issue?