CVE-2026-63374
criticalpriority · track · 0EPSS 0.003 · 21 %ileDEFRUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · high–critical · 8–9.3
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (6)
Products and version ranges known to be affected.
- Red Hat Ansible Automation Platform 2.6all versionscert_bundDEcpe:/a:redhat:ansible_automation_platform:2.6
- Red Hat Ansible Automation Platform 2.7all versionscert_bundDEcpe:/a:redhat:ansible_automation_platform:2.7
advisories (4)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-4111Red Hat Ansible Automation Platform: Mehrere SchwachstellenDeutsch2026-10-21csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Red Hat Ansible Automation Platform ausnutzen, um beliebigen Code mit Benutzer- oder Anwendungsrechten auszuführen, gültige kryptografische Token zu fälschen, die Authentifizierung zu umgehen, erweiterte Rechte zu erlangen, Denial-of-Service-Zustände auszulösen sowie Daten zu manipulieren oder offenzulegen.
- GHSA-82r6-8w77-94w6AnyIO: TLSStream IDNA 2003 host name encoding enables potential TLS certificate spoofing2026-09-18ghsa · osvUS
### Impact Services using internationalized (non-ASCII) domain names are potentially vulnerable to TLS connections made from AnyIO's `connect_tcp()` or directly via `TLSStream.wrap()` where the connection has (through other means) been hijacked and redirected to a malicious server. The attacker would obtain a legitimate certificate using the IDNA 2003 encoded version of the domain name and offer it to the connecting client, making the certificate validate properly on the client's end. ### Patches The vulnerability will be patched in v4.14.2. ### Workarounds Encode host names via the `idna` package prior to connecting.
- CERTFR-2026-AVI-1385Multiples vulnérabilités dans les produits VMwareFrançais2026-10-26vendor · certfrFR
- PYSEC-2026-4025AnyIO: TLSStream IDNA 2003 host name encoding enables potential TLS certificate spoofing2026-10-01vendor · osvUS
### Impact Services using internationalized (non-ASCII) domain names are potentially vulnerable to TLS connections made from AnyIO's `connect_tcp()` or directly via `TLSStream.wrap()` where the connection has (through other means) been hijacked and redirected to a malicious server. The attacker would obtain a legitimate certificate using the IDNA 2003 encoded version of the domain name and offer it to the connecting client, making the certificate validate properly on the client's end. ### Patches The vulnerability will be patched in v4.14.2. ### Workarounds Encode host names via the `idna` package prior to connecting.
also known as (2)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (4) nvd
External citations — patches, advisories, analysis.
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