CVE-2026-97031 (GCVE-0-2026-97031)

Vulnerability from cvelistv5 – Published: 2026-10-08 22:53 – Updated: 2026-10-08 22:53
VLAI
Title
Reject malformed ECH outer extension references in crypto/tls
Summary
Multiple ECH outer extension references are not permitted under RFC 9849; previously, a client could send a well-crafted packet that could trigger memory exhaustion in the server process by specifying multiple references. We now reject these as malformed and curb the memory amplification vector as a result.
Severity
No CVSS data available.
CWE
  • CWE-405 - Asymmetric Resource Consumption
Assigner
Go CNA under the Google root
CNA scorecard E 42/100 over 75 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Go standard library crypto/tls Affected: 0 , < 1.26.9 (semver)
Affected: 1.27.0-0 , < 1.27.2 (semver)
guessed Create a notification for this product.
Show details on NVD website
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "collectionURL": "https://pkg.go.dev",
          "defaultStatus": "unaffected",
          "packageName": "crypto/tls",
          "product": "crypto/tls",
          "programRoutines": [
            {
              "name": "decodeInnerClientHello"
            },
            {
              "name": "Conn.Handshake"
            },
            {
              "name": "Conn.HandshakeContext"
            },
            {
              "name": "Conn.Read"
            },
            {
              "name": "Conn.Write"
            },
            {
              "name": "Dial"
            },
            {
              "name": "DialWithDialer"
            },
            {
              "name": "Dialer.Dial"
            },
            {
              "name": "Dialer.DialContext"
            },
            {
              "name": "QUICConn.Start"
            }
          ],
          "vendor": "Go standard library",
          "versions": [
            {
              "lessThan": "1.26.9",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThan": "1.27.2",
              "status": "affected",
              "version": "1.27.0-0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Multiple ECH outer extension references are not permitted under RFC 9849; previously, a client could send a well-crafted packet that could trigger memory exhaustion in the server process by specifying multiple references. We now reject these as malformed and curb the memory amplification vector as a result."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-405: Asymmetric Resource Consumption",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-08T22:53:58.775Z",
        "orgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
        "shortName": "Go"
      },
      "references": [
        {
          "url": "https://go.dev/cl/847312"
        },
        {
          "url": "https://go.dev/issue/81855"
        },
        {
          "url": "https://groups.google.com/g/golang-announce/c/U2fTuyDJznI"
        },
        {
          "url": "https://pkg.go.dev/vuln/GO-2026-6607"
        }
      ],
      "title": "Reject malformed ECH outer extension references in crypto/tls"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
    "assignerShortName": "Go",
    "cveId": "CVE-2026-97031",
    "datePublished": "2026-10-08T22:53:58.775Z",
    "dateReserved": "2026-09-23T23:03:36.988Z",
    "dateUpdated": "2026-10-08T22:53:58.775Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "collectionURL": "https://pkg.go.dev",
                "defaultStatus": "unaffected",
                "packageName": "crypto/tls",
                "product": "crypto/tls",
                "programRoutines": [
                  {
                    "name": "decodeInnerClientHello"
                  },
                  {
                    "name": "Conn.Handshake"
                  },
                  {
                    "name": "Conn.HandshakeContext"
                  },
                  {
                    "name": "Conn.Read"
                  },
                  {
                    "name": "Conn.Write"
                  },
                  {
                    "name": "Dial"
                  },
                  {
                    "name": "DialWithDialer"
                  },
                  {
                    "name": "Dialer.Dial"
                  },
                  {
                    "name": "Dialer.DialContext"
                  },
                  {
                    "name": "QUICConn.Start"
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                ],
                "vendor": "Go standard library",
                "versions": [
                  {
                    "lessThan": "1.26.9",
                    "status": "affected",
                    "version": "0",
                    "versionType": "semver"
                  },
                  {
                    "lessThan": "1.27.2",
                    "status": "affected",
                    "version": "1.27.0-0",
                    "versionType": "semver"
                  }
                ]
              }
            ],
            "source": "security@golang.org"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Multiple ECH outer extension references are not permitted under RFC 9849; previously, a client could send a well-crafted packet that could trigger memory exhaustion in the server process by specifying multiple references. We now reject these as malformed and curb the memory amplification vector as a result."
          }
        ],
        "id": "CVE-2026-97031",
        "lastModified": "2026-10-08T23:17:06.037",
        "metrics": {},
        "published": "2026-10-08T23:17:06.037",
        "references": [
          {
            "source": "security@golang.org",
            "url": "https://go.dev/cl/847312"
          },
          {
            "source": "security@golang.org",
            "url": "https://go.dev/issue/81855"
          },
          {
            "source": "security@golang.org",
            "url": "https://groups.google.com/g/golang-announce/c/U2fTuyDJznI"
          },
          {
            "source": "security@golang.org",
            "url": "https://pkg.go.dev/vuln/GO-2026-6607"
          }
        ],
        "sourceIdentifier": "security@golang.org",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-10-08T23:25:03+00:00",
      "cve": "CVE-2026-97031",
      "id": "CVE-2026-97031",
      "initial_release_date": "2026-10-08T22:53:58.775000+00:00",
      "product_status:known_affected": "351",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "crypto/tls: golang: crypto/tls: Denial of Service via multiple ECH outer extension references",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-97031.json",
      "version": "3"
    }
  }
}



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