{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "4.14.2"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "f1b7301c8264b0d2e8d24a5788fd29e93dea4040"
            },
            {
              "fixed": "c384f99687c64c59ed8a11c3a0f11a2d57daff71"
            }
          ],
          "repo": "https://github.com/agronholm/anyio",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-5p39-cfhj-2xmp"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64847.json"
  },
  "details": "AnyIO is a high level asynchronous concurrency and networking framework that works on top of either Trio or asyncio. Prior to 4.14.2, AnyIO starts process-pool workers with standard error connected to a pipe that the parent never drains, even though the documented behavior redirects all three standard streams. Worker code that writes enough attacker-influenced data to sys.stderr can fill the pipe and block before returning the standard-output protocol response, causing the awaiting process-pool call to remain blocked indefinitely. Applications that run untrusted or faulty worker code capable of producing substantial standard-error output are affected. This issue is fixed in version 4.14.2.",
  "id": "CVE-2026-64847",
  "modified": "2026-09-20T11:30:41.762387991Z",
  "published": "2026-09-18T17:04:32.038Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/agronholm/anyio/releases/tag/4.14.2"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64847.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/agronholm/anyio/security/advisories/GHSA-5p39-cfhj-2xmp"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64847"
    },
    {
      "type": "FIX",
      "url": "https://github.com/agronholm/anyio/commit/f1b7301c8264b0d2e8d24a5788fd29e93dea4040"
    },
    {
      "type": "FIX",
      "url": "https://github.com/agronholm/anyio/pull/1207"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "AnyIO process-pool workers can block indefinitely on undrained stderr"
}