CVE-2026-23897: Apollo server Denial of Service Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-mp6q-xf9x-fwf7",
  "modified" : "2026-02-04T21:55:11Z",
  "published" : "2026-02-04T18:02:26Z",
  "aliases" : [ "CVE-2026-23897" ],
  "summary" : "Apollo Serve vulnerable to Denial of Service with `startStandaloneServer`",
  "details" : "### Impact\n\nThe default configuration of `startStandaloneServer` from `@apollo/server/standalone` is vulnerable to Denial of Service (DoS) attacks through specially crafted request bodies with exotic character set encodings.\n\nThis issue does not affect users that use `@apollo/server` as a dependency for integration packages, like `@as integrations/express5` or `@as-integrations/next`, only direct usage of `startStandaloneServer`.\n\n### Who is impacted\n\nUsers directly using `startStandaloneServer` from `@apollo/server/standalone`.\n\nThis issue affects Apollo Server from v5.0.0 through v5.3.x.\n\nIt also affects all releases of the end-of-life major versions v4, v3, and v2.  Although Apollo Server v4 is EOL and Apollo no longer commits to providing support or updates for it, a fix for it was released in v4.13.0.  Apollo Server v3 and v2 are no longer updated, as they have been EOL since 2024 and 2023 respectively.\n\n### Patches\n\nPatches for this issue are released as `@apollo/server` versions `5.4.0` and `4.13.0`.\n\nIn accordance with [RFC 7159](https://datatracker.ietf.org/doc/html/rfc7159#section-8.1), these versions now only accept request bodies encoded in UTF-8, UTF-16 (LE or BE), or UTF-32 (LE or BE). Any other character set will be rejected with a `415 Unsupported Media Type` error. Note that the more recent JSON RFC, [RFC 8259 (https://datatracker.ietf.org/doc/html/rfc8259#section-8.1), is more strict and will only allow UTF-8. Since this is a minor release, we have chosen to remain compatible with the more permissive RFC 7159 for now. In a future major release, the restriction may be tightened further to only allow UTF-8.\n\n### Workarounds\n\nUsers of `apollo-server` v2 or v3 that cannot upgrade for some reason could switch from the standalone `apollo-server`\npackage to an integration package like `apollo-server-express` or `apollo-server-koa` and set up their own server. Please note that these old packages are generally EOL and do not receive any more support or bug fixes. This can only be seen as a short-term workaround. Updating to `@apollo/server` v5 should be a priority.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "apollo-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0.0"
      }, {
        "last_affected" : "3.13.0"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@apollo/server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.2.0"
      }, {
        "fixed" : "4.13.0"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@apollo/server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.0.0"
      }, {
        "fixed" : "5.4.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/apollographql/apollo-server/security/advisories/GHSA-mp6q-xf9x-fwf7"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-23897"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/apollographql/apollo-server/commit/d25a5bdc377826ad424fcf7f8d1d062055911643"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/apollographql/apollo-server/commit/e9d49d163a86b8a33be56ed27c494b9acd5400a4"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/apollographql/apollo-server"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1333" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-04T18:02:26Z",
    "nvd_published_at" : "2026-02-04T20:16:05Z"
  }
}