Vulnerability from bitnami_vulndb
Published
2026-10-16 08:40
Modified
2026-10-16 09:07
Summary
HTTP/2 server memory exhaustion due to Trailer headers in net/http
Details

When "Trailer" headers are sent by a client, the HTTP server internally uses the header values to populate the Request.Trailer map passed to the server handler. Because Request.Trailer is a map, each entry incurs memory overhead. For HTTP/2 servers, a malicious client can exploit this by sending a "Trailer" header that declares a large number of fields, causing the server to allocate a disproportionate amount of memory while bypassing Server.MaxHeaderValueCount and Server.MaxHeaderBytes limits. This exploit is not applicable for HTTP/1 servers, which do not support multiplexing a large number of requests over one TCP connection, and whose Server.MaxHeaderBytes are calculated differently.


{
  "affected": [
    {
      "package": {
        "ecosystem": "Bitnami",
        "name": "golang",
        "purl": "pkg:bitnami/golang"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.26.9"
            },
            {
              "introduced": "1.27.0-0"
            },
            {
              "fixed": "1.27.2"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "severity": [
        {
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "type": "CVSS_V3"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-78659"
  ],
  "database_specific": {
    "cpes": [
      "cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*"
    ],
    "severity": "High"
  },
  "details": "When \"Trailer\" headers are sent by a client, the HTTP server internally uses the header values to populate the Request.Trailer map passed to the server handler. Because Request.Trailer is a map, each entry incurs memory overhead. For HTTP/2 servers, a malicious client can exploit this by sending a \"Trailer\" header that declares a large number of fields, causing the server to allocate a disproportionate amount of memory while bypassing Server.MaxHeaderValueCount and Server.MaxHeaderBytes limits. This exploit is not applicable for HTTP/1 servers, which do not support multiplexing a large number of requests over one TCP connection, and whose Server.MaxHeaderBytes are calculated differently.",
  "id": "BIT-golang-2026-78659",
  "modified": "2026-10-16T09:07:50.945Z",
  "published": "2026-10-16T08:40:00.620Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://go.dev/cl/847185"
    },
    {
      "type": "WEB",
      "url": "https://go.dev/cl/847314"
    },
    {
      "type": "WEB",
      "url": "https://go.dev/issue/81857"
    },
    {
      "type": "WEB",
      "url": "https://groups.google.com/g/golang-announce/c/U2fTuyDJznI"
    },
    {
      "type": "WEB",
      "url": "https://groups.google.com/g/golang-announce/c/ZPwCyRUuGBs"
    },
    {
      "type": "WEB",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-78659"
    },
    {
      "type": "WEB",
      "url": "https://pkg.go.dev/vuln/GO-2026-6603"
    }
  ],
  "schema_version": "1.6.2",
  "summary": "HTTP/2 server memory exhaustion due to Trailer headers in net/http"
}



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