pip self-update functionality can import newly installed modules after wheel installation

{
  "id": "9dd23e33483ec1ae40d792a9ffa6258ae6080af3902c0443c34a993c59380874",
  "url": "https://osv.dev/vulnerability/CVE-2026-6357",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "pip self-update functionality can import newly installed modules after wheel installation",
    "summary": "pip prior to version 26.1 would run self-update check functionality after installing wheel files which required importing well-known Python modules names. These module imports were intentionally deferred to increase startup time of the pip CLI. The patch changes self-update functionality to run before wheels are installed to prevent newly-installed modules from being imported shortly after the installation of a wheel package. Users should still review package contents prior to installation.",
    "evidence": "osv:CVE-2026-6357",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-6357",
      "aliases": [
        "CVE-2026-6357",
        "GHSA-jp4c-xjxw-mgf9",
        "PYSEC-2026-2876"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/pypa/pip",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "90b2b3e0f7ef75c485155716d904e51654575803"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "26.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "26.1"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "26.0",
            "21.3",
            "21.0",
            "20.0.2",
            "19.1.1",
            "19.0.2",
            "19.0",
            "18.1",
            "18.0",
            "10.0.1",
            "10.0.0",
            "9.0.1",
            "9.0.0",
            "6.0",
            "1.4rc2",
            "1.4rc1",
            "1.2",
            "1.0",
            "0.8.3",
            "0.8.2",
            "0.8",
            "0.7.1",
            "0.7",
            "0.6",
            "0.3"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-6357.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:27.079290136Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/6xxx/CVE-2026-6357.json",
        "https://ichard26.github.io/blog/2026/04/whats-new-in-pip-26.1/#security-fixes",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-6357",
        "https://github.com/pypa/pip/pull/13923",
        "https://github.com/pypa/pip",
        "https://pypi.org/project/pip"
      ],
      "provider_metadata": {
        "cna_assigner": "PSF",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/6xxx/CVE-2026-6357.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-6357",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 493905,
  "published_at": "2026-04-27T14:19:47.657+00:00"
}