High

python-liquid: Absolute paths escape filesystem loader search path

Disclosed: 11.05.2026
Updated: 11.10.2026 15:17

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.

python

        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.

python

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/"))

Affected software

Click a technology to see all vulnerabilities affecting it.

Platform	Package	Vulnerable versions	Fixed in
Python (PyPI)	python-liquid	< 2.2.0	2.2.0

References

CVSS score 7.5/10

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness (CWE): CWE-22
Platform: Python (PyPI)
Package: python-liquid
Disclosed: 11.05.2026
Updated: 11.10.2026 15:17

Sources and licenses

OSV / GitHub Advisory Database - PYSEC-2026-192 - PyPA Advisory Database; CC BY 4.0

OSV / GitHub Advisory Database - GHSA-8p4x-wr7x-3788 - CC BY 4.0

Vulnerability history: python-liquid

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

Total entries: 2
First → latest: 05.2026 06.2026
Without a fix: 0
Exploited in attacks: 0

Severity breakdown

High 1
Medium 1

Disclosures per year

2026: 2

19.06.2026

Python Liquid: Infinite loop when parsing malformed `{% case %}` tags

Medium CVE-2026-55865 < 2.2.1 2.2.1
11.05.2026

python-liquid: Absolute paths escape filesystem loader search path this entry

High · 7.5 CVE-2026-45017 < 2.2.0 2.2.0

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