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Fencer Intel
critical 9.3

CVE-2026-63374 json

AnyIO: TLSStream IDNA 2003 host name encoding enables potential TLS certificate spoofing

published 4mo ago modified last mo. also EUVD-2026-84522 , GHSA-82r6-8w77-94w6 , PYSEC-2026-4025

cvss
9.3
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 21%
public exploits
0
none known

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, connect_tcp() and TLSStream.wrap() can validate internationalized host names after the standard library converts them with IDNA 2003 instead of IDNA 2008. When a connection to a non-ASCII domain is hijacked or redirected, an attacker can obtain a legitimate certificate for the different ASCII hostname produced by IDNA 2003 and present it to the client, causing the malicious endpoint's certificate to validate. This issue is fixed in version 4.14.2.

Patch / fix

  • pypi anyio 4.14.2
  • python-anyio Debian 14 4.15.1-1

debian advisories DEBIAN-CVE-2026-63374

  • python-anyio SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 4.8.0-160000.3.1
  • python-anyio SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +11 more 4.1.0-150400.9.11.1

suse advisories SUSE-SU-2026:24208-1SUSE-SU-2026:24122-1SUSE-SU-2026:4416-1

  • graphifyy openSUSE Tumbleweed 0.9.97-1.1
  • python-anyio openSUSE Leap 16.0 4.8.0-160000.3.1

opensuse advisories openSUSE-SU-2026:12324-1openSUSE-SU-2026:22060-1

Is CVE-2026-63374 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-63374 updated cvss 7.4

anyio: AnyIO: TLS certificate spoofing via improper internationalized domain name encoding

  • Red Hat Confidential Compute Attestation agent-sandbox/agent-sandbox-router Red Hat Exploit Intelligence exploit-intelligence/vulnerability-analysis-rhel9 Red Hat Lightspeed Core lightspeed-core/rag-tool-cpu-rhel9, lightspeed-core/lightspeed-stack-rhel9, lightspeed-core/rag-tool-cuda-12.9-rhel9 Red Hat Migration Toolkit for Applications 8 mta/mta-solution-server-rhel9 Red Hat Migration Toolkit for Containers rhmtc/openshift-migration-hook-runner-rhel8 Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-ocp-rag-rhel9, openshift-lightspeed/lightspeed-service-api-rhel9, openshift-lightspeed/lightspeed-agentic-sandbox-rhel9, openshift-lightspeed-tech-preview/lightspeed-rag-tool-rhel9
    affected: no fix available
  • Red Hat AI Inference Server rhaii/vllm-tpu-rhel9, rhaiis/vllm-cpu-rhel9, rhaiis/vllm-tpu-rhel9, rhaii/vllm-gaudi-rhel9, rhaii/vllm-neuron-rhel9, rhaiis/vllm-spyre-rhel9, +1 more
    affected: no fix planned “Will not fix”
  • Red Hat Ansible Automation Platform 2 ansible-automation-platform-24/lightspeed-rhel8, ansible-automation-platform-25/lightspeed-rhel8, ansible-automation-platform-26/controller-rhel9, ansible-automation-platform-27/controller-rhel9, ansible-automation-platform-24/ee-supported-rhel8, ansible-automation-platform-24/ee-supported-rhel9, +7 more
    affected: no fix available, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-cuda-rhel9, rhelai3/bootc-rocm-rhel9, rhelai3/bootc-gaudi-rhel9, rhelai3/bootc-aws-cuda-rhel9, rhelai3/bootc-gcp-cuda-rhel9, rhelai3/disk-image-cuda-rhel9, +2 more Red Hat OpenShift AI (RHOAI) rhoai/odh-vllm-gaudi-rhel9, rhoai/odh-llm-d-kv-cache-rhel9, rhoai/odh-llama-stack-core-rhel9, rhoai/odh-caikit-tgis-serving-rhel9, rhai-early-access/docling-sdk-cuda-rhel9, rhai-early-access/docling-serve-cuda-rhel9, +23 more
    affected: no fix available, no fix planned “Will not fix”
  • Red Hat OpenShift Virtualization 4 container-native-virtualization/ocp-virt-validation-checkup-rhel9, openshift-virtualization/konflux-builds/v4-22/ocp-virt-validation-checkup-rhel9 Red Hat OpenStack Platform 18.0 rhoso/openstack-tempest-all-rhel9 Red Hat Satellite 6 satellite/iop-vulnerability-engine-rhel9
    affected: no fix available
  • Red Hat AI Inference Server 3.2 rhaiis/vllm-cuda-rhel9 1790621718, rhaiis/vllm-rocm-rhel9 1790621713
    fixed: vendor fix RHSA-2026:73929
  • Red Hat Ansible Automation Platform 2.6 ansible-automation-platform-26/mcp-tools-rhel9 1791941340, ansible-automation-platform-26/lightspeed-chatbot-rhel9 1791978798
    fixed: vendor fix RHSA-2026:87120
  • Red Hat Ansible Automation Platform 2.7 ansible-automation-platform-27/mcp-tools-rhel9 1790931895, ansible-automation-platform-27/de-supported-rhel9 1792143400, ansible-automation-platform-27/lightspeed-chatbot-rhel9 1792385971
    fixed: vendor fix RHSA-2026:87124
show 11 more
  • Red Hat OpenShift AI 2.25 rhoai/odh-ta-lmes-job-rhel9 1791553527
    fixed: vendor fix RHSA-2026:87410
  • Red Hat OpenShift AI 3.4 rhoai/odh-automl-rhel9 1791535789, rhoai/odh-autorag-rhel9 1791557539, rhoai/odh-mlserver-rhel9 1793110755, rhoai/odh-ta-lmes-job-rhel9 1791470318, rhoai/odh-kserve-agent-rhel9 1791468381, rhoai/odh-kserve-router-rhel9 1791468401, +14 more
    fixed: vendor fix RHSA-2026:84734
  • Red Hat OpenShift AI 3.5 rhoai/odh-ta-lmes-job-rhel9 1792501995, rhoai/odh-feature-server-rhel9 1791864484, rhoai/odh-built-in-detector-rhel9 1791790996, rhoai/odh-th-torch-cpu-py312-rhel9 1791926611, rhoai/odh-training-rocm64-torch28-py312-rhel9 1791906128, rhoai/odh-training-rocm64-torch29-py312-rhel9 1791926972, +3 more
    fixed: vendor fix RHSA-2026:86891
  • Red Hat Satellite 6.18 satellite/iop-vmaas-rhel9 1793197689, satellite/foreman-mcp-server-rhel9 1793272276, satellite/iop-host-inventory-rhel9 1793248583
    fixed: vendor fix RHSA-2026:92667
  • Red Hat Satellite 6.19 satellite/iop-vmaas-rhel9 1793197872, satellite/foreman-mcp-server-rhel9 1793272279, satellite/iop-host-inventory-rhel9 1793248689
    fixed: vendor fix RHSA-2026:92666
  • Red Hat Trusted Artifact Signer 1.5 rhtas/rh-sigstore-a2a-rhel9 1793624122
    fixed: vendor fix RHSA-2026:95267
  • Red Hat Ansible Automation Orchestrator 2026 ansible-automation-platform/automation-orchestrator-backend-rhel9 Red Hat Lightspeed Services for Advanced Cluster Management lightspeed-services-acm/ocp-rules-rhel9 Red Hat AI Inference Server rhaii/vllm-cpu-rhel9, rhaii/vllm-cuda-rhel9, rhaii/vllm-rocm-rhel9, rhaii/vllm-spyre-rhel9, rhaii/model-opt-cuda-rhel9 Red Hat Ansible Automation Platform 2 ansible-automation-platform-26/eda-controller-rhel9, ansible-automation-platform-27/eda-controller-rhel9 Red Hat Ansible Automation Platform 2.6 ansible-automation-platform-26/hub-rhel9 1791947385, ansible-automation-platform-26/gateway-rhel9 1791971533, ansible-automation-platform-26/hub-web-rhel9 1791952205, ansible-automation-platform-26/receptor-rhel9 1791968536, ansible-automation-platform-26/controller-rhel9 1791947602, ansible-automation-platform-26/de-minimal-rhel9 1791961810, +23 more Red Hat Ansible Automation Platform 2.7 ansible-automation-platform-27/hub-rhel9 1791254555, ansible-automation-platform-27/hub-rhel9 1792388670, ansible-automation-platform-27/gateway-rhel9 1791257377, ansible-automation-platform-27/gateway-rhel9 1792429216, ansible-automation-platform-27/hub-web-rhel9 1791264503, ansible-automation-platform-27/hub-web-rhel9 1792394496, +57 more
    +1 more products
    Red Hat Enterprise Linux command line assistant rhel-cla/rhel-knowledge-bridge-rhel10
    not affected: vulnerable code not present
  • Red Hat Hardened Images jaeger 2.20.0-0.11.hum1, openshell 0.1.2-0.1.hum1, python-urllib3 2.8.0-1.hum1, python-attrs 26.1.0-4.1.hum1, python-gitlab 8.6.0-1.1.hum1
    not affected: component not present
  • Red Hat Lightspeed Services for OCP lightspeed-services-ocp/ocp-rules-rhel9 Red Hat OpenShift AI (RHOAI) rhai/guidellm-rhel9, rhoai/odh-mlflow-rhel9, rhoai/odh-ogx-core-rhel9, rhoai/odh-caikit-nlp-rhel9, rhoai/odh-mlserver-cuda-rhel9, rhoai/odh-th-torch-cuda-py312-rhel9, +4 more Red Hat OpenShift AI 2.25 rhoai/odh-rhel9-operator 1792570619, rhoai/odh-vllm-cpu-rhel9 1792018436, rhoai/odh-dashboard-rhel9 1791853525, rhoai/odh-modelmesh-rhel9 1790881700, rhoai/odh-operator-bundle 1792571069, rhoai/odh-vllm-cuda-rhel9 1791358976, +65 more Red Hat OpenShift AI 3.4 rhoai/odh-cli-rhel9 1791509689, rhoai/odh-cli-rhel9 1792722177, rhoai/rhai-cli-rhel9 1791509689, rhoai/rhai-cli-rhel9 1792722177, rhoai/odh-automl-rhel9 1792697253, rhoai/odh-mlflow-rhel9 1791865967, +186 more Red Hat OpenShift AI 3.5 rhoai/odh-cli-rhel9 1791945905, rhoai/rhai-cli-rhel9 1791945905, rhoai/odh-automl-rhel9 1791916705, rhoai/odh-mlflow-rhel9 1791947857, rhoai/odh-autorag-rhel9 1791903266, rhoai/odh-trainer-rhel9 1791952138, +104 more
    not affected: vulnerable code not present
  • Red Hat OpenStack Platform 18.0 python-anyio 3.5.0-3.el9ost
    not affected: vulnerable code not in execute path
  • Red Hat Satellite 6 satellite/iop-advisor-engine-rhel9
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
last mo.

Exploit prediction

0.29% chance of exploitation in the next 30 days, higher than 21% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 9.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
CNA 4.0 9.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem package affected fixed in
pypi anyio
<4.14.2
4.14.2

Affected products

  • agronholm anyio

Classification

Weakness
  • CWE-295 Improper Certificate Validation
  • CWE-297 Improper Validation of Certificate with Host Mismatch

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of agronholm/anyio published their own advisory on GitHub. Reviewed sources take precedence over it.