CVE-2026-55688: Async http client AsyncHttpClient Stores Cookie For An Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-m452-q8c9-rg2f",
  "modified" : "2026-08-26T14:35:52Z",
  "published" : "2026-08-26T14:35:52Z",
  "aliases" : [ "CVE-2026-55688" ],
  "summary" : "AsyncHttpClient stores cookie for an unrelated domain (cookie tossing) via ThreadSafeCookieStore",
  "details" : "### Impact\n A **cookie tossing / cookie injection** issue (CWE-1275). `ThreadSafeCookieStore` stored a cookie under the value of its `Domain` attribute without verifying that the responding host is allowed to set a cookie for that domain (RFC 6265 §5.3 step 6). A host the client connects to can therefore plant a cookie scoped to an unrelated domain, and the client will then send that cookie on later requests to that domain.\n\n### Who is Impacted\nApplications that use a single `AsyncHttpClient` instance - and thus the default, shared `CookieStore` - to reach **both** an attacker-influenced host and a trusted host. Typical exposure: crawlers, link-preview / webhook fetchers, SSRF-style \"fetch this URL\" features, multi-backend aggregators, or following redirects to an attacker-controlled host. The attacker can *write* a cookie the client presents to the victim host (session fixation, overwriting a session id / CSRF-token cookie); they cannot *read* the victim host's cookies. Applications that talk only to a fixed trusted backend, or that disable/scope the cookie store, are not exposed.\n\n### Patches\nFixed in 3.0.11 and 2.16.0\n\n### Workarounds\n- Disable the cookie store (setCookieStore(null)) when cookies are not needed; or\n- Use a separate AsyncHttpClient (separate cookie store) per trust domain so an attacker-influenced host and a trusted host never share a jar\n- Supply a custom CookieStore whose add(Uri, Cookie) rejects cookies whose Domain is not domain-matched by the request host.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.asynchttpclient:async-http-client"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.0.0.Beta1"
      }, {
        "fixed" : "3.0.11"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.asynchttpclient:async-http-client"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0.0"
      }, {
        "fixed" : "2.16.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/AsyncHttpClient/async-http-client/security/advisories/GHSA-m452-q8c9-rg2f"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-55688"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/AsyncHttpClient/async-http-client/pull/2196"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/AsyncHttpClient/async-http-client/pull/2199"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/AsyncHttpClient/async-http-client/commit/8e4069cf3c92abe099db5fb13378ac2fe9e1fd3b"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/AsyncHttpClient/async-http-client/commit/e6955c1e3951cf80e286981d064f6c926ce33f47"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/AsyncHttpClient/async-http-client"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/AsyncHttpClient/async-http-client/releases/tag/async-http-client-project-2.16.0"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/AsyncHttpClient/async-http-client/releases/tag/async-http-client-project-3.0.11"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2026/08/msg00011.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1275" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-26T14:35:52Z",
    "nvd_published_at" : "2026-07-01T20:17:11Z"
  }
}