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.
CVE-2026-64847
“—” beside the score: it is equal to the CVSS score beside it.
This medium-severity CVE scores 6.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2% (4th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
Also known asEUVD-2026-83193 (ENISA EUVD) · GHSA-5p39-cfhj-2xmp (GitHub Security Advisories) · PYSEC-2026-4024 (OSV.dev)Source: ENISA EUVD
- Lower severity and no public exploit yet
A fix is available — apply it.
- CVSS v3
- 6.8
- EG Score
- 6.8MEDIUMmedium confidence
- EG Risk
- 31EG Risk 31/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity68% × 45%Impact severity (EG Severity): CVSS 6.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.2% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- 0.2%
- EPSS %ILE
- 4th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (6.8): severity, escalated by confirmed exploitation. This CVE's 6.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 6.8 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
September 18, 2026
Last Modified
September 24, 2026
Advisory Details (4)
Auto-updated Sep 18, 20264.14.2
Patch available: agronholm/anyio 4.14.2
https://github.com/agronholm/anyio/releases/tag/4.14.2commit f1b7301c8264 (agronholm/anyio)
Patch available: agronholm/anyio 4.14.2 (contains commit f1b7301c8264)
https://github.com/agronholm/anyio/commit/f1b7301c8264b0d2e8d24a5788fd29e93dea4040Fixed stderr writes in a worker subprocess causing a deadlock
Patch available: agronholm/anyio 4.14.2 (PR #1207 merged 2026-07-08)
https://github.com/agronholm/anyio/pull/1207AnyIO process-pool workers can block indefinitely on undrained stderr · Advisory · agronholm/anyio · GitHub
Affected: v4.14.2.
https://github.com/agronholm/anyio/security/advisories/GHSA-5p39-cfhj-2xmpVendor Advisories for CVE-2026-64847(8)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2026:73930Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat AI Inference Server 3.2.2 (rocm)
- RHSA-2026:73929Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat AI Inference Server 3.2.2 (cuda)
- RHSA-2026:70996Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat AI Inference Model Optimization Tools 3.4.5 (cuda)
- RHSA-2026:70995Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat AI Inference 3.4.5 (rocm)
- RHSA-2026:70979Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat AI Inference 3.4.5 (cuda)
- RHSA-2026:70969Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat AI Inference 3.4.5 (spyre)
- RHSA-2026:70965Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat AI Inference 3.4.5 (cpu)
- GHSA-5p39-cfhj-2xmpGitHub Security AdvisoriesMedium
AnyIO process-pool workers can block indefinitely on undrained stderr
Patch Availability(8)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| redhat | rhaiis/vllm-cuda-rhel9:1790621718 | 2026-09-30 | redhat |
| redhat | rhaiis/vllm-rocm-rhel9:1790621713 | 2026-09-30 | redhat |
| redhat | rhaii/vllm-cpu-rhel9:1790075793 | 2026-09-23 | redhat |
| redhat | rhaii/vllm-spyre-rhel9:1790076141 | 2026-09-23 | redhat |
| redhat | rhaii/vllm-cuda-rhel9:1790090131 | 2026-09-23 | redhat |
| redhat | rhaii/vllm-rocm-rhel9:1790109620 | 2026-09-23 | redhat |
| redhat | rhaii/model-opt-cuda-rhel9:1790076498 | 2026-09-23 | redhat |
| pip | anyio @ 4.14.2 (fixes < 4.14.2) | — | ghsa |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(4 across 4 ecosystems)
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python-anyio | 3.6.2-1 ... 4.8.0-3 (24 versions) |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python-anyio | 4.11.0-1 ... 4.8.0-3 (10 versions) |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python-anyio | 4.11.0-1 ... 4.8.0-3 (7 versions) |
| — |
PyPI(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| anyio | 1.0.0 ... 4.9.0 (69 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 10× in last 7d / 55× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 1 repeat row among the latest 87 is merged into the row it repeats.
- 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-11-01 07:40 UTCGHSA enrichmentGHSA-5p39-cfhj-2xmp · GitHub severity MODERATE
- 2026-11-01 07:40 UTCEG score recompute
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-30 08:25 UTCOSV refresh
- 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-25 14:12 UTCEG score recompute
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-22 19:42 UTCEG score recompute
- 2026-10-22 19:42 UTCVendor advisory
- 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-18 03:22 UTCEG score recompute
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-16 16:43 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
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- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-12 15:47 UTCEG score recompute
- 2026-10-11 19:32 UTCEG score recompute
- 2026-10-11 17:04 UTCVendor advisory
- 2026-10-11 16:47 UTCEG score recompute
- 2026-10-11 14:08 UTCEG score recompute
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-10 17:32 UTCEG score recompute
- 2026-10-10 17:32 UTCVendor advisory
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-09 17:53 UTCVendor advisory
- 2026-10-08 17:32 UTCEG score recompute
- 2026-10-08 17:32 UTCVendor advisory
- 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-07 18:00 UTCVendor advisory
- 2026-10-06 16:34 UTCEG score recompute
- 2026-10-06 16:34 UTCVendor advisory
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-05 16:59 UTCEG score recompute
- 2026-10-05 16:59 UTCVendor advisory
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-04 17:27 UTCVendor advisory
- 2026-10-03 17:56 UTCEG score recompute
- 2026-10-03 17:56 UTCVendor advisory
- 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-02 18:22 UTCEG score recompute
- 2026-10-02 18:22 UTCVendor advisory
- 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-01 18:50 UTCVendor advisory
- 2026-09-30 18:59 UTCEG score recompute
- 2026-09-30 18:59 UTCVendor advisory
- 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-09-29 19:28 UTCEG score recompute
- 2026-09-29 19:28 UTCVendor advisory
- 2026-09-28 19:50 UTCEG score recompute
- 2026-09-28 19:50 UTCVendor advisory
- 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-09-27 20:16 UTCEG score recompute
- 2026-09-27 20:16 UTCVendor advisory
- 2026-09-26 20:44 UTCEG score recompute
- 2026-09-26 20:44 UTCVendor advisory
- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-09-25 21:11 UTCVendor advisory
- 2026-09-24 21:38 UTCVendor advisory
- 2026-09-24 15:41 UTCEG score recompute
- 2026-09-24 15:41 UTCVendor advisory
- 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-09-22 16:38 UTCEG score recompute
- 2026-09-21 17:06 UTCEG score recompute
- 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
- 2026-09-19 18:01 UTCEG score recompute
- 2026-09-18 18:27 UTCEG score recompute
- 2026-09-18 18:15 UTCEG score recompute
- 2026-09-18 17:19 UTCEG score recomputeFirst assessed: 6.8 MEDIUM
- 2026-09-18 17:19 UTCMITRE cvelistV5first tracked
Related CVEs(same product + same vendor + same CWE)
Same vendor
10 shownredhat:RHSA-2026:70965
Frequently asked(5)
What is CVE-2026-64847?
When was the CVE record for CVE-2026-64847 published?
Is CVE-2026-64847 actively exploited?
What is the CVSS score of CVE-2026-64847?
How do I remediate CVE-2026-64847?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-64847
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