{"id":"CVE-2026-64847","title":"AnyIO is a high level asynchronous concurrency and networking framework that works on top of either Trio or asyncio","summary":"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,…","severity":"medium","cvss":6.8,"cvssVector":"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","cwe":["CWE-770"],"vendor":"agronholm","product":"anyio","affected":["anyio < 4.14.2"],"patched":["anyio 4.14.2"],"published":"2026-09-18","updated":"2026-09-18","sourceUpdated":"2026-09-18T18:17:10.930","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-64847","references":[{"url":"https://github.com/agronholm/anyio/commit/f1b7301c8264b0d2e8d24a5788fd29e93dea4040","label":"security-advisories@github.com"},{"url":"https://github.com/agronholm/anyio/pull/1207","label":"security-advisories@github.com"},{"url":"https://github.com/agronholm/anyio/releases/tag/4.14.2","label":"security-advisories@github.com"},{"url":"https://github.com/agronholm/anyio/security/advisories/GHSA-5p39-cfhj-2xmp","label":"security-advisories@github.com"},{"url":"https://github.com/advisories/GHSA-5p39-cfhj-2xmp"},{"url":"https://github.com/agronholm/anyio"}],"tags":["nvd","cve.org","ghsa","pip","osv"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-18T18:07:19.030895Z"},"cvssSource":"cna","aliases":["GHSA-5p39-cfhj-2xmp"],"ecosystem":"pip","ingestedAt":"2026-09-18T17:46:41.530Z","epss":0.00121,"epssPercentile":0.02219,"slug":"CVE-2026-64847","body":"## Overview\n\nAnyIO 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Package advisory (CVE-2026-64847)\n\nAffected packages:\n\n- `anyio < 4.14.2`\n\nPatched in:\n\n- `anyio 4.14.2`\n\nSource: https://github.com/advisories/GHSA-5p39-cfhj-2xmp","depth":"sunlit","depthScore":37,"depthScoreParts":{"impact":37.4,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}