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CVE-2026-63374

CVE-2026-63374 · AnyIO: TLSStream IDNA 2003 host name encoding enables potential TLS certificate spoofing

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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 9.3 · Critical · EPSS 0.3% · Fix available

Published
Updated

Stack: system · python

Affected products and versions

  • anyio

    Versions
    • < 4.14.2: Affected

    No fix published

  • python-anyio Debian:12

    Versions
    • 3.6.2-1
    • 3.7.0-1
    • 4.1.0-1
    • 4.11.0-1
    • 4.11.0-2
    • 4.11.0-3
    • 4.12.1-1
    • 4.12.1-2
    • 4.12.1-3
    • 4.15.1-1
    • 4.15.1-2
    • 4.15.1-3
    • 4.2.0-1
    • 4.3.0-1
    • 4.4.0-1
    • 4.6.0-1
    • 4.6.2-1
    • 4.6.2-2
    • 4.6.2-3
    • 4.6.2-4
    • 4.7.0-1
    • 4.8.0-1
    • 4.8.0-2
    • 4.8.0-3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • python-anyio Debian:13

    Versions
    • 4.11.0-1
    • 4.11.0-2
    • 4.11.0-3
    • 4.12.1-1
    • 4.12.1-2
    • 4.12.1-3
    • 4.15.1-1
    • 4.15.1-2
    • 4.15.1-3
    • 4.8.0-3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • python-anyio Debian:14

    Versions
    • 4.11.0-1
    • 4.11.0-2
    • 4.11.0-3
    • 4.12.1-1
    • 4.12.1-2
    • 4.12.1-3
    • 4.8.0-3
    Affected ranges
    • ECOSYSTEM: < 4.15.1-1

    Update to 4.15.1-1

  • anyio PyPI

    Versions
    • 1.0.0
    • 1.0.0a1
    • 1.0.0a2
    • 1.0.0b1
    • 1.0.0b2
    • 1.0.0rc1
    • 1.0.0rc2
    • 1.1.0
    • 1.2.0
    • 1.2.1
    • 1.2.2
    • 1.2.3
    • 1.3.0
    • 1.3.1
    • 1.4.0
    • 2.0.0
    • 2.0.0b1
    • 2.0.0b2
    • 2.0.0rc1
    • 2.0.0rc2
    • 2.0.1
    • 2.0.2
    • 2.1.0
    • 2.2.0
    • 3.0.0
    • 3.0.0rc1
    • 3.0.0rc2
    • 3.0.0rc3
    • 3.0.0rc4
    • 3.0.1
    • 3.1.0
    • 3.2.0
    • 3.2.1
    • 3.3.0
    • 3.3.1
    • 3.3.2
    • 3.3.3
    • 3.3.4
    • 3.4.0
    • 3.5.0
    • 3.6.0
    • 3.6.1
    • 3.6.2
    • 3.7.0
    • 3.7.0rc1
    • 3.7.1
    • 4.0.0
    • 4.0.0rc1
    • 4.1.0
    • 4.10.0
    • 4.11.0
    • 4.12.0
    • 4.12.1
    • 4.13.0
    • 4.14.0
    • 4.14.1
    • 4.2.0
    • 4.3.0
    • 4.4.0
    • 4.5.0
    • 4.5.1
    • 4.5.2
    • 4.6.0
    • 4.6.1
    • 4.6.2
    • 4.6.2.post1
    • 4.7.0
    • 4.8.0
    • 4.9.0
    Affected ranges
    • ECOSYSTEM: < 4.14.2

    Update to 4.14.2

  • python-anyio Ubuntu:22.04:LTS

    Versions
    • 2.0.2-2
    • 3.5.0-2ubuntu1
    • 3.5.0-3ubuntu2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • python-anyio Ubuntu:24.04:LTS

    Versions
    • 3.7.0-1
    • 4.2.0-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • python-anyio Ubuntu:26.10

    Versions
    • 4.11.0-3
    • 4.12.1-2
    • 4.12.1-3
    • 4.15.1-3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • python-anyio Ubuntu:26.04:LTS

    Versions
    • 4.8.0-3
    • 4.11.0-2
    • 4.11.0-3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

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