AnyIO process-pool workers can block indefinitely on undrained stderr
Priority LOW 29CWE-770Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 2 fixed, 15 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-770.
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, 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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00157 4th percentileScored 2026-11-07
Fix Partial anyio (agronholm): 4.14.2anyio (PyPI): 4.14.2Red Hat: 7 advisoriesRed Hat: 2 fixed, 15 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| agronholm | anyio | before 4.14.2 | 4.14.2 | Patch available | CNA |
| — | anyio (PyPI) | before 4.14.2 | 4.14.2 | Patch available | GHSA-5p39-cfhj-2xmp |
- anyio Vendoragronholm Affected before 4.14.2 Fixed in 4.14.2 Patch available CNA
- anyio (PyPI) Vendor— Affected before 4.14.2 Fixed in 4.14.2 Patch available GHSA-5p39-cfhj-2xmp
Remediation
- Fix · CNA anyio (agronholm) Fixed in 4.14.2
- Fix · GHSA-5p39-cfhj-2xmp anyio (PyPI) Fixed in 4.14.2 Advisory →
Red Hat 7 advisories
- RHSA-2026:73930 Released 2026-09-30 · Red Hat rating ImportantRed Hat AI Inference Server 3.2.2 (rocm)
- Red Hat AI Inference Server 3.2 registry.redhat.io/rhaiis/vllm-rocm-rhel9
- RHSA-2026:73929 Released 2026-09-30 · Red Hat rating ImportantRed Hat AI Inference Server 3.2.2 (cuda)
- Red Hat AI Inference Server 3.2 registry.redhat.io/rhaiis/vllm-cuda-rhel9
- RHSA-2026:70996 Released 2026-09-23 · Red Hat rating ImportantRed Hat AI Inference Model Optimization Tools 3.4.5 (cuda)
- Red Hat AI Inference Server 3.4 registry.redhat.io/rhaii/model-opt-cuda-rhel9
Show 4 more Red Hat advisories
- RHSA-2026:70995 Released 2026-09-23 · Red Hat rating ImportantRed Hat AI Inference 3.4.5 (rocm)
- Red Hat AI Inference Server 3.4 registry.redhat.io/rhaii/vllm-rocm-rhel9
- RHSA-2026:70979 Released 2026-09-23 · Red Hat rating ImportantRed Hat AI Inference 3.4.5 (cuda)
- Red Hat AI Inference Server 3.4 registry.redhat.io/rhaii/vllm-cuda-rhel9
- RHSA-2026:70969 Released 2026-09-23 · Red Hat rating ImportantRed Hat AI Inference 3.4.5 (spyre)
- Red Hat AI Inference Server 3.4 registry.redhat.io/rhaii/vllm-spyre-rhel9
- RHSA-2026:70965 Released 2026-09-23 · Red Hat rating ImportantRed Hat AI Inference 3.4.5 (cpu)
- Red Hat AI Inference Server 3.4 registry.redhat.io/rhaii/vllm-cpu-rhel9
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Ansible Automation Orchestrator 2026 | Affected | No fix yet: Fix deferred |
| Confidential Compute Attestation | Affected | No fix yet: Fix deferred |
| Exploit Intelligence | Affected | No fix planned: Out of support scope |
| Lightspeed Core | Affected | No fix yet: Fix deferred |
| Migration Toolkit for Applications 8 | Affected | No fix yet: Fix deferred |
| Migration Toolkit for Containers | Affected | No fix yet: Fix deferred |
| OpenShift Lightspeed | Affected | No fix yet: Fix deferred |
| Red Hat AI Inference Server | Affected | No fix yet: Fix deferred |
| Red Hat Ansible Automation Platform 2 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux command line assistant | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Virtualization 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenStack Platform 18.0 | Affected | No fix yet: Fix deferred |
| Red Hat Satellite 6 | Affected | No fix yet: Fix deferred |
| Red Hat AI Inference Server 3.2 | Fixed | RHSA-2026:73929, RHSA-2026:73930 |
| Red Hat AI Inference Server 3.4 | Fixed | RHSA-2026:70965, RHSA-2026:70969, RHSA-2026:70979, RHSA-2026:70995, RHSA-2026:70996 |
Not affected: 1 product
- Red Hat Hardened Images
Timeline
- 2026-10-02 Threatist record created from CVE-2026-64847
- 2026-10-03 Alias added: GHSA-5p39-cfhj-2xmp
References
More agronholm vulnerabilities
- TI-2026-21200 cbor2 has a Denial of Service via Uncontrolled Recursion in cbor2.loads CVSS 3.0HIGH 7.5
- TI-2024-17225 CBOR2 decoder has potential buffer overflow CVSS 3.1HIGH 7.5
- TI-2025-39535 Multiple vulnerabilities exist in cbor2 through version 5.7.0 in the… CVSS 3.1HIGH 7.5
- TI-2025-41712 CBORDecoder reuse can leak shareable values across decode calls CVSS 4.0MEDIUM 5.5
- TI-2026-45177 AnyIO: TLSStream IDNA 2003 host name encoding enables potential TLS certificate spoofing CVSS 4.0CRITICAL 9.3
- TI-2026-45170 AnyIO run_process/open_process ignores extra_groups and can retain parent supplementary groups CVSS 4.0HIGH 7.0
Sources
- CVE-2026-64847 · CVE Program
- CVE-2026-64847 · NVD
- FIRST EPSS
- GHSA-5p39-cfhj-2xmp · GitHub Advisory Database · CC BY 4.0
- CVE-2026-64847 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences