CVE-2026-63374 (GCVE-0-2026-63374)

Vulnerability from cvelistv5 – Published: 2026-09-22 15:23 – Updated: 2026-09-22 15:23
VLAI
Title
AnyIO: TLSStream IDNA 2003 host name encoding enables potential TLS certificate spoofing
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.
Severity
9.3 (Critical)
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
CWE
  • CWE-295 - Improper Certificate Validation
  • CWE-297 - Improper Validation of Certificate with Host Mismatch
Assigner
References
Impacted products
Vendor Product Version CPE status
agronholm anyio Affected: < 4.14.2
guessed Create a notification for this product.
Show details on NVD website
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{
  "containers": {
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      "affected": [
        {
          "product": "anyio",
          "vendor": "agronholm",
          "versions": [
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          "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\u0027s certificate to validate. This issue is fixed in version 4.14.2."
        }
      ],
      "metrics": [
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            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
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            "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",
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            }
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        },
        {
          "descriptions": [
            {
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              "description": "CWE-297: Improper Validation of Certificate with Host Mismatch",
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              "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": [
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          "url": "https://github.com/agronholm/anyio/security/advisories/GHSA-82r6-8w77-94w6"
        },
        {
          "name": "https://github.com/agronholm/anyio/pull/1208",
          "tags": [
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          "url": "https://github.com/agronholm/anyio/pull/1208"
        },
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          "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": [
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          ],
          "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"
  },
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  "dataVersion": "5.2",
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      "date": "2026-09-24",
      "epss": "0.00289",
      "percentile": "0.19067"
    },
    "nvd": {
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                    "version": "\u003c 4.14.2"
                  }
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          }
        ],
        "id": "CVE-2026-63374",
        "lastModified": "2026-09-24T21:16:28.120",
        "metrics": {
          "cvssMetricV40": [
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                "Recovery": "NOT_DEFINED",
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                "attackVector": "NETWORK",
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                "confidentialityRequirement": "NOT_DEFINED",
                "exploitMaturity": "NOT_DEFINED",
                "integrityRequirement": "NOT_DEFINED",
                "modifiedAttackComplexity": "NOT_DEFINED",
                "modifiedAttackRequirements": "NOT_DEFINED",
                "modifiedAttackVector": "NOT_DEFINED",
                "modifiedPrivilegesRequired": "NOT_DEFINED",
                "modifiedSubAvailabilityImpact": "NOT_DEFINED",
                "modifiedSubConfidentialityImpact": "NOT_DEFINED",
                "modifiedSubIntegrityImpact": "NOT_DEFINED",
                "modifiedUserInteraction": "NOT_DEFINED",
                "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
                "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
                "modifiedVulnIntegrityImpact": "NOT_DEFINED",
                "privilegesRequired": "NONE",
                "providerUrgency": "NOT_DEFINED",
                "subAvailabilityImpact": "NONE",
                "subConfidentialityImpact": "NONE",
                "subIntegrityImpact": "NONE",
                "userInteraction": "NONE",
                "valueDensity": "NOT_DEFINED",
                "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/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",
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                "vulnerabilityResponseEffort": "NOT_DEFINED"
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        "vulnStatus": "Awaiting Analysis",
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    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-09-23T00:24:23Z",
      "cve": "CVE-2026-63374",
      "id": "CVE-2026-63374",
      "initial_release_date": "2026-09-21T16:50:09Z",
      "product_status:known_affected": "60",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-63374",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-63374.json",
      "version": "3"
    }
  }
}



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