GHSA-qq6c-99pv-prvf

Опубликовано: 11 июн. 2026

Источник: github

Github: Прошло ревью

CVSS4: 8.4

Описание

PDM: Project-Controlled .pdm-plugins Content Executes Before CLI Parsing

Summary

PDM automatically loads project-local plugin paths from .pdm-plugins during Core initialization. Because this path is added via site.addsitedir(), attacker-controlled .pth files inside the project plugin directory are processed and can execute Python code before normal CLI handling begins.

This allows arbitrary code execution with the privileges of the user running pdm from an untrusted repository checkout.

Affected Behavior

Trigger does not require pdm install --plugins
A low-impact command such as pdm --version is sufficient
Impact is strongest in CI, privileged shells, and automation contexts

Affected Code

src/pdm/core.py:74-82
src/pdm/core.py:310-333
src/pdm/core.py:335-352

Technical Details

Core.__init__() calls load_plugins() before ordinary command execution. load_plugins() calls _add_project_plugins_library(), which derives the project-local .pdm-plugins library path and adds it through site.addsitedir().

On CPython, site.addsitedir() processes .pth files found in the added directory. .pth lines beginning with import are executed immediately. This creates a trust-boundary break: project-controlled files execute before the user explicitly opts into plugin installation or plugin loading.

Impact

Arbitrary code execution as the invoking user
Potential credential theft, persistence, or workspace tampering
Potential privilege escalation when pdm is run via sudo, root-owned CI jobs, or privileged service accounts

Reproduction

PoC:

# Replace this with a Python interpreter that can run `python -m pdm`. PDM_PY=/path/to/python-with-pdm tmpdir=$(mktemp -d) cat > "$tmpdir/pyproject.toml" <<'EOF' [project] name = "plugin-autoload-demo" version = "0.0.1" EOF purelib=$(TMPDIR_ROOT="$tmpdir/.pdm-plugins" "$PDM_PY" - <<'PY' import os import sys import sysconfig base = os.environ["TMPDIR_ROOT"] scheme_names = sysconfig.get_scheme_names() if (sys.platform == "darwin" and "osx_framework_library" in scheme_names) or sys.platform == "linux": scheme = "posix_prefix" elif sys.version_info < (3, 10): scheme = "nt" if os.name == "nt" else "posix_prefix" else: scheme = sysconfig.get_default_scheme() replace_vars = {"base": base, "platbase": base} print(sysconfig.get_path("purelib", scheme, replace_vars)) PY ) mkdir -p "$purelib" marker="$tmpdir/plugin-autoload-marker.txt" printf '%s\n' "import pathlib; pathlib.Path(r'$marker').write_text('project plugin autoload executed', encoding='utf-8')" > "$purelib/evil.pth" ( cd "$tmpdir" && "$PDM_PY" -m pdm --version ) cat "$marker"

Expected result:

A temporary project is created
An evil.pth file is placed under .pdm-plugins
Running pdm --version creates a marker file before CLI exit

Observed output from local validation:

PDM, version 2.26.9 --- marker --- project plugin autoload executed

Severity

High

CVSS v4.0

Base score: 8.4 (High)
Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Rationale:

AV:L: exploitation occurs through local execution of pdm against attacker-controlled repository content
AC:L: no special bypass or race is required
AT:N: no external precondition beyond the vulnerable workflow is required
PR:N: the attacker does not need privileges on the victim host
UI:A: the victim must actively run a pdm command in the malicious checkout
VC:H/VI:H/VA:H: successful exploitation yields arbitrary code execution as the invoking user
SC:N/SI:N/SA:N: the score is kept to same-system impact only

Root Cause

Project-local plugin paths are implicitly trusted and loaded too early, and .pth processing is inherited from site.addsitedir().

Recommended Remediation

Do not auto-load project-local .pdm-plugins by default
Avoid site.addsitedir() for project-controlled plugin paths
If project plugins must be supported, require explicit opt-in such as --enable-project-plugins
Explicitly prevent .pth execution when loading project plugin paths

Disclosure Notes

This issue is a strong standalone CVE candidate because it yields direct code execution from repository-controlled files without requiring the victim to run a project script explicitly.

Ссылки

Пакеты

Наименование

pdm

pip

Затронутые версииВерсия исправления

<= 2.26.9

2.27.0

EPSS

Процентиль: 3%

0.00131

Низкий

8.4 High

CVSS4

CVE ID

CVE-2026-47781

Дефекты

CWE-94

Связанные уязвимости

CVE-2026-47781

ubuntu

6 дней назад

PDM is a Python package and dependency manager. In versions up to and including 2.26.9, PDM automatically loads project-local plugins from a .pdm-plugins directory during initialization, allowing an attacker-controlled file in an untrusted repository checkout to execute arbitrary Python code before any command is parsed. This happens because load_plugins() runs during Core.init() and adds .pdm-plugins via site.addsitedir(), which processes .pth files and immediately executes any line beginning with import, so the code runs with the privileges of the user invoking pdm and even a benign command such as pdm --version triggers it (making the impact strongest in CI, automation, and privileged contexts). The issue is fixed in version 2.27.0.