CVE-2026-26994

{
  "id": "CVE-2026-26994",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
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        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-26994",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-02-20T15:12:10.465682Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "security-advisories@github.com",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 6.5,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "LOW"
        },
        "impactScore": 2.5,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "security-advisories@github.com",
      "affectedData": [
        {
          "vendor": "refraction-networking",
          "product": "utls",
          "versions": [
            {
              "status": "affected",
              "version": "< 1.7.0"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-02-20T03:16:01.330",
  "references": [
    {
      "url": "https://github.com/refraction-networking/utls/commit/f8892761e2a4d29054264651d3a86fda83bc83f9",
      "tags": [
        "Patch"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/refraction-networking/utls/issues/181",
      "tags": [
        "Issue Tracking"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/refraction-networking/utls/pull/337",
      "tags": [
        "Issue Tracking",
        "Patch"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/refraction-networking/utls/security/advisories/GHSA-pmc3-p9hx-jq96",
      "tags": [
        "Patch",
        "Vendor Advisory"
      ],
      "source": "security-advisories@github.com"
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  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security-advisories@github.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-693"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "uTLS is a fork of crypto/tls, created to customize ClientHello for fingerprinting resistance while still using it for the handshake. In versions 1.6.7 and below, uTLS did not implement the TLS 1.3 downgrade protection mechanism specified in RFC 8446 Section 4.1.3 when using a uTLS ClientHello spec. This allowed an active network adversary to downgrade TLS 1.3 connections initiated by a uTLS client to a lower TLS version (e.g., TLS 1.2) by modifying the ClientHello message to exclude the SupportedVersions extension, causing the server to respond with a TLS 1.2 ServerHello (along with a downgrade canary in the ServerHello random field). Because uTLS did not check the downgrade canary in the ServerHello random field, clients would accept the downgraded connection without detecting the attack. This attack could also be used by an active network attacker to fingerprint uTLS connections. This issue has been fixed in version 1.7.0."
    },
    {
      "lang": "es",
      "value": "uTLS es una bifurcación de crypto/tls, creado para personalizar ClientHello con el fin de resistir la identificación de huellas digitales mientras se sigue utilizando para el protocolo de enlace. En las versiones 1.6.7 y anteriores, uTLS no implementó el mecanismo de protección contra la degradación de TLS 1.3 especificado en la Sección 4.1.3 de RFC 8446 cuando se utiliza una especificación de ClientHello de uTLS. Esto permitió a un adversario de red activo degradar las conexiones TLS 1.3 iniciadas por un cliente de uTLS a una versión de TLS inferior (por ejemplo, TLS 1.2) modificando el mensaje ClientHello para excluir la extensión SupportedVersions, haciendo que el servidor responda con un ServerHello de TLS 1.2 (junto con un 'canary' de degradación en el campo aleatorio de ServerHello). Debido a que uTLS no verificó el 'canary' de degradación en el campo aleatorio de ServerHello, los clientes aceptarían la conexión degradada sin detectar el ataque. Este ataque también podría ser utilizado por un atacante de red activo para la huella digital de conexiones uTLS. Este problema ha sido solucionado en la versión 1.7.0."
    }
  ],
  "lastModified": "2026-06-17T10:26:30.400",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
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              "criteria": "cpe:2.3:a:refraction-networking:utls:*:*:*:*:*:go:*:*",
              "vulnerable": true,
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              "versionEndExcluding": "1.7.0"
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