PT-2026-39696 · Pypi · Python-Liquid

Published

2026-05-11

·

Updated

2026-05-11

·

CVE-2026-45017

CVSS v4.0

8.2

High

VectorAV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Impact

The built-in FileSystemLoader and CachingFileSystemLoader do not guard against reading files outside their search paths when given an absolute path to resolve. This allows malicious template authors to load and render arbitrary files via the {% include %} and {% render %} tags. Targeted files would need to contain valid Liquid markup and be readable by the application process.

Patches

The issue is fixed in version 2.2.0 with the inclusion of a template path.is absolute() condition in liquid/builtin/loaders/file system loader.py.
    if os.path.pardir in template path.parts or template path.is absolute():
      raise TemplateNotFoundError(template name)

Workarounds

Create a custom template loader by inheriting from FileSystemLoader and overriding resolve path(). Use an instance of the custom loader as the loader argument when instantiating your Liquid environment.
import os
from pathlib import Path

from liquid import Environment
from liquid import FileSystemLoader
from liquid.exceptions import TemplateNotFoundError


class MyFileSystemLoader(FileSystemLoader):
  def resolve path(self, template name: str) -> Path:
    template path = Path(template name)

    if self.ext and not template path.suffix:
      template path = template path.with suffix(self.ext)

    if os.path.pardir in template path.parts or template path.is absolute():
      raise TemplateNotFoundError(template name)

    for path in self.search path:
      source path = path.joinpath(template path)
      if not source path.exists():
        continue
      return source path

    raise TemplateNotFoundError(template name)


env = Environment(loader=MyFileSystemLoader("path/to/templates/"))

Fix

Path traversal

Weakness Enumeration

CWE-22

Related Identifiers

CVE-2026-45017
GHSA-8P4X-WR7X-3788

Affected Products

Python-Liquid