Vulnerability-Lookup

GHSA-8RJX-V5WW-45PP

Vulnerability from github – Published: 2026-10-21 16:39 – Updated: 2026-10-21 16:39

Summary

virtualenv activation scripts run code from a path that contains a placeholder name

Details

Impact

ViaTemplateActivator.instantiate_template replaces the placeholders in an activation template one key at a time, each across the whole text. When a value that it already substituted and quoted contains the name of a later placeholder, the later pass rewrites that name inside the quoted literal. The inserted value brings its own quotes, which close the outer literal, and the rest of the path runs as code when a user activates the environment.

__VIRTUAL_NAME__ holds the environment's directory name, so a destination such as A__VIRTUAL_NAME__B/x'$(touch PWNED)'y is enough. In the default activate for bash, the VIRTUAL_ENV line renders as:

VIRTUAL_ENV='/tmp/t/A'x'"'"'$(touch PWNED)'"'"'y'B/x'"'"'$(touch PWNED)'"'"'y'

Sourcing that script runs touch PWNED. The same payload in a path without the placeholder name runs nothing. activate.fish runs the command the same way, and the reporter also showed Python code execution through activate.xsh and bin/activate_this.py. In activate.csh, a directory named after a prompt display placeholder, such as __VIRTUAL_PROMPT_DISPLAY_TCSH__, breaks the script with Unmatched '''.

No change to quote() can stop this, because the rewrite happens after quote() ran; it defeats shlex.quote and repr() alike.

An attacker needs to influence the destination path or --prompt: a CI job or wrapper tool that builds the path from a branch or project name, or a directory in a cloned repository or unpacked archive.

The bug affects versions 20.26.6 through 21.14.1. Version 20.26.6 first quoted template values (#2768) and introduced the per-key loop.

Patches

Fixed in 21.14.2. Activation scripts now keep a placeholder name in the environment's path or prompt as plain text, and activating the example above runs nothing. Fix: https://github.com/pypa/virtualenv/commit/602b26623a724827ff171bf11fef4ad186d01f74

Workarounds

Do not create an environment whose path or --prompt contains a placeholder name such as __VIRTUAL_NAME__, __VIRTUAL_ENV__ or __VIRTUAL_PROMPT__, and inspect the generated activation script before you source one you did not create.

Credits

Kevin Stubbings (@Kwstubbs) of GitHub Security Lab reported this issue.

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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JSON

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 21.14.1"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "virtualenv"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "20.26.6"
            },
            {
              "fixed": "21.14.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-113776"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-78",
      "CWE-94"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-21T16:39:38Z",
    "nvd_published_at": "2026-10-20T22:19:30Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\n`ViaTemplateActivator.instantiate_template` replaces the placeholders in an activation template one key at a time, each across the whole text. When a value that it already substituted and quoted contains the name of a later placeholder, the later pass rewrites that name inside the quoted literal. The inserted value brings its own quotes, which close the outer literal, and the rest of the path runs as code when a user activates the environment.\n\n`__VIRTUAL_NAME__` holds the environment\u0027s directory name, so a destination such as `A__VIRTUAL_NAME__B/x\u0027$(touch PWNED)\u0027y` is enough. In the default `activate` for bash, the `VIRTUAL_ENV` line renders as:\n\n```sh\nVIRTUAL_ENV=\u0027/tmp/t/A\u0027x\u0027\"\u0027\"\u0027$(touch PWNED)\u0027\"\u0027\"\u0027y\u0027B/x\u0027\"\u0027\"\u0027$(touch PWNED)\u0027\"\u0027\"\u0027y\u0027\n```\n\nSourcing that script runs `touch PWNED`. The same payload in a path without the placeholder name runs nothing. `activate.fish` runs the command the same way, and the reporter also showed Python code execution through `activate.xsh` and `bin/activate_this.py`. In `activate.csh`, a directory named after a prompt display placeholder, such as `__VIRTUAL_PROMPT_DISPLAY_TCSH__`, breaks the script with `Unmatched \u0027\u0027\u0027`.\n\nNo change to `quote()` can stop this, because the rewrite happens after `quote()` ran; it defeats `shlex.quote` and `repr()` alike.\n\nAn attacker needs to influence the destination path or `--prompt`: a CI job or wrapper tool that builds the path from a branch or project name, or a directory in a cloned repository or unpacked archive.\n\nThe bug affects versions 20.26.6 through 21.14.1. Version 20.26.6 first quoted template values (#2768) and introduced the per-key loop.\n\n### Patches\n\nFixed in 21.14.2. Activation scripts now keep a placeholder name in the environment\u0027s path or prompt as plain text, and activating the example above runs nothing. Fix: https://github.com/pypa/virtualenv/commit/602b26623a724827ff171bf11fef4ad186d01f74\n\n### Workarounds\n\nDo not create an environment whose path or `--prompt` contains a placeholder name such as `__VIRTUAL_NAME__`, `__VIRTUAL_ENV__` or `__VIRTUAL_PROMPT__`, and inspect the generated activation script before you source one you did not create.\n\n### Credits\n\nKevin Stubbings (@Kwstubbs) of GitHub Security Lab reported this issue.",
  "id": "GHSA-8rjx-v5ww-45pp",
  "modified": "2026-10-21T16:39:38Z",
  "published": "2026-10-21T16:39:38Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pypa/virtualenv/security/advisories/GHSA-8rjx-v5ww-45pp"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-113776"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/virtualenv/commit/602b26623a724827ff171bf11fef4ad186d01f74"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pypa/virtualenv"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/virtualenv/releases/tag/21.14.2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "virtualenv activation scripts run code from a path that contains a placeholder name"
}

CVE-2026-113776 (GCVE-0-2026-113776)

Vulnerability from cvelistv5 – Published: 2026-10-20 22:03 – Updated: 2026-10-20 22:03

Title

virtualenv activation scripts run code from a path that contains a placeholder name

Summary

virtualenv is a tool for creating isolated virtual python environments. From 20.26.6 until 21.14.2, ViaTemplateActivator.instantiate_template() replaces placeholders one key at a time across the complete activation template, so trigger names such as __VIRTUAL_NAME__, __VIRTUAL_ENV__, or __VIRTUAL_PROMPT__ inside an already substituted and quoted environment path or prompt can be replaced during a later pass. The later value's quoting can close the earlier literal and execute the remaining path when a user activates the environment through bash, fish, xonsh, or activate_this.py. The distinct csh prompt-display token __VIRTUAL_PROMPT_DISPLAY_TCSH__ can instead break the generated script without establishing command execution. The attacker must influence the destination path or --prompt, and a value without a relevant placeholder name does not trigger this mechanism. This issue is fixed in version 21.14.2.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CWE

CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
CWE-94 - Improper Control of Generation of Code ('Code Injection')

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7630 records in the last 180 days details

References

3 references

URL	Tags
https://github.com/pypa/virtualenv/security/advis…	x_refsource_CONFIRM
https://github.com/pypa/virtualenv/commit/602b266…	x_refsource_MISC
https://github.com/pypa/virtualenv/releases/tag/21.14.2	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
pypa	virtualenv	Affected: >= 20.26.6, < 21.14.2

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "virtualenv",
          "vendor": "pypa",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 20.26.6, \u003c 21.14.2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "virtualenv is a tool for creating isolated virtual python environments. From 20.26.6 until 21.14.2, ViaTemplateActivator.instantiate_template() replaces placeholders one key at a time across the complete activation template, so trigger names such as __VIRTUAL_NAME__, __VIRTUAL_ENV__, or __VIRTUAL_PROMPT__ inside an already substituted and quoted environment path or prompt can be replaced during a later pass. The later value\u0027s quoting can close the earlier literal and execute the remaining path when a user activates the environment through bash, fish, xonsh, or activate_this.py. The distinct csh prompt-display token __VIRTUAL_PROMPT_DISPLAY_TCSH__ can instead break the generated script without establishing command execution. The attacker must influence the destination path or --prompt, and a value without a relevant placeholder name does not trigger this mechanism. This issue is fixed in version 21.14.2."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-78",
              "description": "CWE-78: Improper Neutralization of Special Elements used in an OS Command (\u0027OS Command Injection\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-94",
              "description": "CWE-94: Improper Control of Generation of Code (\u0027Code Injection\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-20T22:03:18.274Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/pypa/virtualenv/security/advisories/GHSA-8rjx-v5ww-45pp",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/pypa/virtualenv/security/advisories/GHSA-8rjx-v5ww-45pp"
        },
        {
          "name": "https://github.com/pypa/virtualenv/commit/602b26623a724827ff171bf11fef4ad186d01f74",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/pypa/virtualenv/commit/602b26623a724827ff171bf11fef4ad186d01f74"
        },
        {
          "name": "https://github.com/pypa/virtualenv/releases/tag/21.14.2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/pypa/virtualenv/releases/tag/21.14.2"
        }
      ],
      "source": {
        "advisory": "GHSA-8rjx-v5ww-45pp",
        "discovery": "UNKNOWN"
      },
      "title": "virtualenv activation scripts run code from a path that contains a placeholder name"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-113776",
    "datePublished": "2026-10-20T22:03:18.274Z",
    "dateReserved": "2026-10-20T17:39:41.371Z",
    "dateUpdated": "2026-10-20T22:03:18.274Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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