{"id":"CVE-2026-64847","summary":"AnyIO process-pool workers can block indefinitely on undrained stderr","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.","aliases":["GHSA-5p39-cfhj-2xmp"],"modified":"2026-09-20T11:47:14.870140750Z","published":"2026-09-18T17:04:32.038Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64847.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-770"]},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/agronholm/anyio","events":[{"introduced":"0"},{"fixed":"f1b7301c8264b0d2e8d24a5788fd29e93dea4040"},{"fixed":"c384f99687c64c59ed8a11c3a0f11a2d57daff71"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"4.14.2"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["4.14.1","4.14.0","4.13.0","4.12.0","4.11.0","4.10.0","4.9.0","4.8.0","4.7.0","4.6.2.post1","4.6.2","4.6.1","4.5.0","4.6.0","4.4.0","4.3.0","4.2.0","4.1.0","4.0.0","4.0.0rc1","3.6.1","3.6.0","3.5.0","3.4.0","3.3.4","3.3.3","3.3.2","3.3.1","3.3.0","3.2.1","3.2.0","3.1.0","3.0.1","3.0.0","3.0.0rc4","3.0.0rc3","3.0.0rc2","3.0.0rc1","2.1.0","2.0.2","2.0.1","2.0.0","2.0.0rc2","2.0.0rc1","2.0.0b2","2.0.0b1","1.4.0","1.3.1","1.3.0","1.2.3","1.2.2","1.2.1","1.2.0","1.1.0","1.0.0","1.0.0rc2","1.0.0rc1","1.0.0b2","1.0.0b1","1.0.0a2","1.0.0a1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64847.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","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"}]}