Checksum database bypass for golang.org/toolchain in cmd/go

{
  "id": "624e648e5e1acf08ee617b2f89e3366137301ddc30d57872bf0a24a94ff80fc9",
  "url": "https://osv.dev/vulnerability/BIT-golang-2026-94447",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Checksum database bypass for golang.org/toolchain in cmd/go",
    "summary": "Previously, a user operating inside of a malicious Go project that defines a bogus golang.org/toolchain go.sum entry and operates a malicious GOMODPROXY the user chooses to use can bypass the intended checksum. We now ensure that golang.org/toolchain always goes to the network for the canonical checksum.",
    "evidence": "osv:BIT-golang-2026-94447",
    "products": [
      {
        "name": {
          "value": "golang",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.26.9",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "1.27.2",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "BIT-golang-2026-94447",
      "aliases": [
        "BIT-golang-2026-94447",
        "CVE-2026-94447",
        "GO-2026-6602"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.26.9"
                },
                {
                  "introduced": "1.27.0-0"
                },
                {
                  "fixed": "1.27.2"
                }
              ]
            }
          ],
          "package": {
            "name": "golang",
            "purl": "pkg:bitnami/golang",
            "ecosystem": "Bitnami"
          },
          "severity": [
            {
              "type": "CVSS_V3",
              "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
            }
          ],
          "database_specific": {
            "source": "https://github.com/bitnami/vulndb/tree/main/data/golang/BIT-golang-2026-94447.json"
          }
        }
      ],
      "modified": "2026-10-16T09:55:44.518918993Z",
      "provider": "osv",
      "references": [
        "https://go.dev/cl/840785",
        "https://go.dev/issue/81834",
        "https://groups.google.com/g/golang-announce/c/U2fTuyDJznI",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-94447",
        "https://pkg.go.dev/vuln/GO-2026-6602"
      ],
      "provider_metadata": {
        "cpes": [
          "cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*"
        ],
        "severity": "High"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-94447",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 338703,
  "published_at": "2026-10-16T08:40:11.458+00:00"
}