{"id":"CVE-2026-64847","state":"PUBLISHED","title":"AnyIO process-pool workers can block indefinitely on undrained stderr","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.","publishedAt":"2026-09-18T17:04:32.038Z","updatedAt":"2026-09-18T18:07:27.772Z","severity":{"score":6.8,"label":"Medium","version":"4.0","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","source":"GitHub_M"},"assigner":"GitHub_M","products":["agronholm anyio"],"affected":[{"vendor":"agronholm","product":"anyio","versions":[{"version":"< 4.14.2","status":"affected"}]}],"references":["https://github.com/agronholm/anyio/security/advisories/GHSA-5p39-cfhj-2xmp","https://github.com/agronholm/anyio/pull/1207","https://github.com/agronholm/anyio/commit/f1b7301c8264b0d2e8d24a5788fd29e93dea4040","https://github.com/agronholm/anyio/releases/tag/4.14.2"],"weaknesses":["CWE-770"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64847.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64847","state":"PUBLISHED","datePublished":"2026-09-18T17:04:32.038Z","dateUpdated":"2026-09-18T18:07:27.772Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-07-20T18:31:39.290Z"},"containers":{"cna":{"title":"AnyIO process-pool workers can block indefinitely on undrained stderr","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"agronholm","product":"anyio","versions":[{"version":"< 4.14.2","status":"affected"}]}],"references":[{"url":"https://github.com/agronholm/anyio/security/advisories/GHSA-5p39-cfhj-2xmp","name":"https://github.com/agronholm/anyio/security/advisories/GHSA-5p39-cfhj-2xmp","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/agronholm/anyio/pull/1207","name":"https://github.com/agronholm/anyio/pull/1207","tags":["x_refsource_MISC"]},{"url":"https://github.com/agronholm/anyio/commit/f1b7301c8264b0d2e8d24a5788fd29e93dea4040","name":"https://github.com/agronholm/anyio/commit/f1b7301c8264b0d2e8d24a5788fd29e93dea4040","tags":["x_refsource_MISC"]},{"url":"https://github.com/agronholm/anyio/releases/tag/4.14.2","name":"https://github.com/agronholm/anyio/releases/tag/4.14.2","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"LOCAL","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"LOW","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":6.8,"baseSeverity":"MEDIUM","vectorString":"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","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-770","lang":"en","description":"CWE-770: Allocation of Resources Without Limits or Throttling","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-18T17:04:32.038Z"},"source":{"advisory":"GHSA-5p39-cfhj-2xmp","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-18T18:07:19.030895Z","id":"CVE-2026-64847","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-18T18:07:27.772Z"}}]}}}