virtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration injection

{
  "id": "978393bb2da29c9ac5b9f4fb92cb510e87125d5ca7ff4f4a525fae11288f18e2",
  "url": "https://osv.dev/vulnerability/CVE-2026-102938",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "virtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration injection",
    "summary": "virtualenv is a tool for creating isolated virtual python environments. Prior to 21.7.11, PyEnvCfg.write() writes prompt values verbatim to the line-oriented pyvenv.cfg format while PyEnvCfg._read_values() parses the file with str.splitlines() and accepts the last value for duplicate keys. An attacker who influences --prompt, VIRTUALENV_PROMPT, or configuration input can insert a recognized line boundary and additional keys, including home, causing consumers to use an attacker-selected base interpreter or corrupted environment metadata. The security impact requires prompt input from outside the operator's trust boundary; directly supplied prompt content primarily corrupts the operator's own environment. This issue is fixed in version 21.7.11.",
    "evidence": "osv:CVE-2026-102938",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-102938",
      "aliases": [
        "BIT-virtualenv-2026-102938",
        "CVE-2026-102938",
        "GHSA-9h9j-4vrj-gf7g",
        "PYSEC-2026-4012"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/pypa/virtualenv",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "73e352ae02bfa52ffc0e307b04f1b6a7168c4eb0"
                },
                {
                  "fixed": "a30f995461043acb6cacbf3a890951563ccf7140"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "21.7.11"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "a30f995461043acb6cacbf3a890951563ccf7140"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "73e352ae02bfa52ffc0e307b04f1b6a7168c4eb0"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "21.7.11"
                  }
                ]
              }
            }
          ],
          "versions": [
            "21.7.10",
            "21.7.9",
            "21.7.8",
            "21.7.7",
            "21.7.6",
            "21.7.5",
            "21.7.4",
            "21.7.3",
            "21.7.2",
            "21.7.1",
            "21.7.0",
            "21.6.1",
            "21.6.0",
            "21.5.2",
            "21.5.1",
            "21.5.0",
            "21.4.3",
            "21.4.2",
            "21.4.1",
            "21.4.0",
            "21.3.3",
            "21.3.2",
            "21.3.1",
            "21.3.0",
            "21.2.4",
            "21.2.3",
            "21.2.2",
            "21.2.1",
            "21.2.0",
            "21.1.0",
            "21.0.0",
            "20.39.1",
            "20.39.0",
            "20.38.0",
            "20.37.0",
            "20.27.3",
            "20.27.2",
            "20.24.3",
            "20.3.0",
            "20.0.32",
            "20.0.7",
            "20.0.0b2",
            "20.0.0b1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-102938.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:38.417504315Z",
      "provider": "osv",
      "references": [
        "https://github.com/pypa/virtualenv/releases/tag/21.7.11",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102938.json",
        "https://github.com/pypa/virtualenv/security/advisories/GHSA-9h9j-4vrj-gf7g",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-102938",
        "https://github.com/pypa/virtualenv/commit/a30f995461043acb6cacbf3a890951563ccf7140",
        "https://github.com/pypa/virtualenv/pull/3247"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-93"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102938.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-102938",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 505760,
  "published_at": "2026-09-29T20:58:20.696+00:00"
}