CVE-2026-63374

Description

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.

Overview

State: PUBLISHED
Assigner (CNA): GitHub_M
CVSS severity: CRITICAL
CVSS score: 9.3 / 10
CVSS vector: 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
Effective score: 9.3 / 10 CRITICAL source: CNA overview
CWE(s): CWE-295, CWE-297
Reserved: 2026-07-16
Published: 2026-09-22 15:23 UTC
Last updated: 2026-09-22 15:23 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/63xxx/CVE-2026-63374.json
Linked Threat: CVE-2026-63374 — AnyIO: TLSStream IDNA 2003 host name encoding enables potential TLS certificate spoofing

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-09-22 16:17:50 UTC
NVD last modified: 2026-09-22 16:17:50 UTC

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-84522
Assigner: GitHub_M
Published: Sep 22, 2026, 3:23:14 PM
Updated: Sep 22, 2026, 3:23:14 PM
EUVD base score (CVSS 4.0): 9.3 / 10
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
EUVD-reported EPSS: 0.0000
Vendors: agronholm
Products: anyio (< 4.14.2)
Aliases: GHSA-82r6-8w77-94w6

ENISA description: 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.

EUVD references (4)

Affected products (1)

Vendor	Product	Versions	Platforms
agronholm	anyio	`< 4.14.2` (affected)	—

Vendor references (4)

References embedded in the original CVE record by the assigning CNA.

https://github.com/agronholm/anyio/security/advisories/GHSA-82r6-8w77-94w6 x_refsource_CONFIRM
https://github.com/agronholm/anyio/pull/1208 x_refsource_MISC
https://github.com/agronholm/anyio/commit/68f58915f82d9be8109ebbbd8f5d70577d43f2ce x_refsource_MISC
https://github.com/agronholm/anyio/releases/tag/4.14.2 x_refsource_MISC

Web references (0)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

No web references attached yet.

NVD-tagged references (4)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://github.com/agronholm/anyio/commit/68f58915f82d9be8109ebbbd8f5d70577d43f2ce security-advisories@github.com
https://github.com/agronholm/anyio/pull/1208 security-advisories@github.com
https://github.com/agronholm/anyio/releases/tag/4.14.2 security-advisories@github.com
https://github.com/agronholm/anyio/security/advisories/GHSA-82r6-8w77-94w6 security-advisories@github.com

Remediations (10)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

CVE-2026-63374 - Exploits & Severity - Feedly

web:feedly.com

Sep 18, 2026 at 10:21 AM / GitHub Advisory Database CVE assignment NVD published the first details for CVE-2026-63374

2026-09-23 15:18 UTC
CVE-2026-63374 | Security Details | Sonatype Guide

web:guide.sonatype.com

Technical security analysis for CVE-2026-63374 . CVSS 9.3 severity. View CVSS vectors, CWE classifications, and exploit maturity ratings.

2026-09-23 15:18 UTC
Microsoft Patch Tracker (September 2026): Exploit-Ranked | Senserva

web:senserva.com

Every Microsoft security patch (KB) and the CVEs it fixes, with severity, CVSS, and CISA KEV status. Cross-linked to the CVE reference.

2026-09-23 15:18 UTC
SAP Security Patch Day - April 2026

web:support.sap.com

SAP security patch day bulletin This post shares the information on security notes that remediate vulnerabilities discovered in SAP products. SAP strongly recommends that the customer visits the support portal and applies patches on priority to protect their SAP landscape. On 14 th of April 2026 , SAP security patch day saw the release of 19 new security notes. There is 1 update to previously ...

2026-09-23 15:18 UTC
SAP Security Patch Day - June 2026

web:support.sap.com

SAP security Patch Day Bulletin This post shares the information on security notes that remediate vulnerabilities discovered in SAP products. SAP strongly recommends that the customer visits the support portal and applies patches on priority to protect their SAP landscape. On 9th of June 2026 , SAP security patch day saw the release of 15 new security notes.

2026-09-23 15:18 UTC
CVE-2026-63374 - vulnerability database | Vulners.com

web:vulners.com

CVE-2026-63374 🗓️ 22 Sep 2026 08:23:14 Reported by GitHub_M Type cve 🔗 web.nvd.nist.gov 👁 102 Views

2026-09-23 15:18 UTC
CVE-2026-93374 - Detail CVSS, EPSS & CISA Kev | CVE Find

web:www.cvefind.com

Full details for CVE - 2026 -93374: technical description, impact, CVSS/EPSS scores, linked CWE, CAPEC, affected CPEs, disclosure date, and mitigation options.

2026-09-23 15:18 UTC
DSA-2026-374: Security Update for Dell iDRAC9 Vulnerability

web:www.dell.com

Dell iDRAC9 remediation for an Improper Access Control security vulnerability that could be exploited by malicious users to compromise the affected system.

2026-09-23 15:18 UTC
Security Bulletin: IBM i is Affected By Multiple Vulnerabilities in NTP

web:www.ibm.com

The fix introduces evhttp_parse_headers_impl_ and a temporary trailer header list. An unauthenticated remote attacker can place security-sensitive fields in trailers so that an upstream proxy and the libevent application interpret different effective headers, enabling header smuggling, authorization bypass, proxy-header spoofing, or cache ...

2026-09-23 15:18 UTC
Oracle Critical Patch Update Advisory - July 2026

web:www.oracle.com

This Critical Patch Update contains 1448 new security patches across the product families listed below. Please note that a My Oracle Support (MOS) note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at July 2026 Critical Patch Update: Executive Summary and Analysis.

2026-09-23 15:18 UTC

AI Forensic Analysis

Only Available for Registered Users. Sign in to view.

Raw JSON

The full cvelistV5 record. Download as CVE-2026-63374.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "anyio",
          "vendor": "agronholm",
          "versions": [
            {
              "status": "affected",
              "version": "< 4.14.2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 9.3,
            "baseSeverity": "CRITICAL",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "HIGH"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-295",
              "description": "CWE-295: Improper Certificate Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-297",
              "description": "CWE-297: Improper Validation of Certificate with Host Mismatch",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-22T15:23:14.259Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/agronholm/anyio/security/advisories/GHSA-82r6-8w77-94w6",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/agronholm/anyio/security/advisories/GHSA-82r6-8w77-94w6"
        },
        {
          "name": "https://github.com/agronholm/anyio/pull/1208",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/agronholm/anyio/pull/1208"
        },
        {
          "name": "https://github.com/agronholm/anyio/commit/68f58915f82d9be8109ebbbd8f5d70577d43f2ce",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/agronholm/anyio/commit/68f58915f82d9be8109ebbbd8f5d70577d43f2ce"
        },
        {
          "name": "https://github.com/agronholm/anyio/releases/tag/4.14.2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/agronholm/anyio/releases/tag/4.14.2"
        }
      ],
      "source": {
        "advisory": "GHSA-82r6-8w77-94w6",
        "discovery": "UNKNOWN"
      },
      "title": "AnyIO: TLSStream IDNA 2003 host name encoding enables potential TLS certificate spoofing"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-63374",
    "datePublished": "2026-09-22T15:23:14.259Z",
    "dateReserved": "2026-07-16T17:39:30.170Z",
    "dateUpdated": "2026-09-22T15:23:14.259Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}