{"cve":"CVE-2026-64847","nvd":{"published":"2026-09-18T18:17:10.930","modified":"2026-09-24T21:25:27.050","status":"Deferred","description":"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.","cvss_v4":{"vector":"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","score":6.8},"cvss_v3":null,"cwes":["CWE-770"],"references":["https://github.com/agronholm/anyio/commit/f1b7301c8264b0d2e8d24a5788fd29e93dea4040","https://github.com/agronholm/anyio/pull/1207","https://github.com/agronholm/anyio/releases/tag/4.14.2","https://github.com/agronholm/anyio/security/advisories/GHSA-5p39-cfhj-2xmp"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:55:23.253742848+00:00"},"epss":{"cve":"CVE-2026-64847","score":0.00157,"percentile":0.04787,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-5p39-cfhj-2xmp","url":"https://osv.dev/vulnerability/GHSA-5p39-cfhj-2xmp","summary":"AnyIO process-pool workers can block indefinitely on undrained stderr","modified":"2026-10-01T17:55:57.336188727Z","packages":[{"ecosystem":"PyPI","name":"anyio","purl":"pkg:pypi/anyio","ranges":["<4.14.2"],"fixed":["4.14.2"]}]},{"id":"PYSEC-2026-4024","url":"https://osv.dev/vulnerability/PYSEC-2026-4024","summary":"AnyIO process-pool workers can block indefinitely on undrained stderr","modified":"2026-10-01T17:45:01.995149284Z","packages":[{"ecosystem":"PyPI","name":"anyio","purl":"pkg:pypi/anyio","ranges":["<4.14.2"],"fixed":["4.14.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}