CVE-2026-8468: Plug Denial of Service Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-468c-vq7p-gh64",
  "modified" : "2026-05-20T15:35:13Z",
  "published" : "2026-05-20T15:35:13Z",
  "aliases" : [ "CVE-2026-8468" ],
  "summary" : "Plug: Unbounded buffer accumulation in multipart header parsing causes denial of service",
  "details" : "### Summary\n\nAn Allocation of Resources Without Limits or Throttling vulnerability in `Plug.Conn.read_part_headers/2` allows an unauthenticated attacker to exhaust server memory by sending a crafted `multipart/form-data` request, causing a denial of service.\n\n### Details\n\n`Plug.Conn.read_part_headers/2` in `lib/plug/conn.ex` does not obey its `:length` parameter. There is no upper bound on the size of the accumulated buffer. By contrast, the sibling function `read_part_body` has an explicit `byte_size(acc) > length` guard that stops accumulation once a limit is reached. No such guard exists in `read_part_headers`.\n\n### Impact\n\nThis is a denial-of-service vulnerability. Any application using `Plug.Parsers` with the `:multipart` parser, or calling `Plug.Conn.read_part_headers/2` directly, is affected. An unauthenticated remote attacker can trigger the issue by sending crafted HTTP requests with no special privileges.\n\n### References\n\n* Intro Commit: https://github.com/elixir-plug/plug/commit/c52b2f32c90bccd718202bafccb5f95594e30183\n* Patch Commit: https://github.com/elixir-plug/plug/commit/d878b42efea9f12b243dc3e362a2ed048a798203",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Hex",
      "name" : "plug"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.4.0"
      }, {
        "fixed" : "1.15.4"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Hex",
      "name" : "plug"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.16.0"
      }, {
        "fixed" : "1.16.3"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Hex",
      "name" : "plug"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.17.0"
      }, {
        "fixed" : "1.17.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Hex",
      "name" : "plug"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.18.0"
      }, {
        "fixed" : "1.18.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Hex",
      "name" : "plug"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.19.0"
      }, {
        "fixed" : "1.19.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/elixir-plug/plug/security/advisories/GHSA-468c-vq7p-gh64"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-8468"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/elixir-plug/plug/commit/2cb7958d33030aa826b0c7404375844d4593d43a"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/elixir-plug/plug/commit/33858427c7f2737d560a2e40a0c9a9270d77d1d7"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/elixir-plug/plug/commit/aa69c5ece99c40ded88b8c6581ecc86664b0b734"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/elixir-plug/plug/commit/d5dfffe25e975585227b1b85d247b0d14164bc45"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/elixir-plug/plug/commit/df812a1527bae9e941965e897308a2b8bbf83a94"
  }, {
    "type" : "WEB",
    "url" : "https://cna.erlef.org/cves/CVE-2026-8466.html"
  }, {
    "type" : "WEB",
    "url" : "https://cna.erlef.org/cves/CVE-2026-8468.html"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/elixir-plug/plug"
  }, {
    "type" : "WEB",
    "url" : "https://osv.dev/vulnerability/EEF-CVE-2026-8468"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-20T15:35:13Z",
    "nvd_published_at" : "2026-05-14T11:16:18Z"
  }
}