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async-http-client — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2026-55688

The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. In versions from 2.0.0 prior to 2.16.0 and from 3.0.0.Beta1 prior to 3.0.11, 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, leading to a cookie tossing / cookie injection issue. 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. Applications that use a single AsyncHttpClient instance - and thus the default, shared CookieStore - to reach both an attacker-influenced host and a trusted host are impacted. This issue has been fixed in versions 2.16.0 and 3.0.11.

Products
async-http-client
Affected versions
2.12.3-1
Fixed versions
2.12.3-1+deb12u1
CVEs
CVE-2026-55688
Confirmed fixed CVEs
Not specified
Updated in this feed
1 Nov 2026, 12:22 UTC · Revision 2

Source evidence

DEBIAN-CVE-2026-55688

core-osv · Original source

Published 1 Jul 2026, 20:17 UTC

The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. In versions from 2.0.0 prior to 2.16.0 and from 3.0.0.Beta1 prior to 3.0.11, 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, leading to a cookie tossing / cookie injection issue. 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. Applications that use a single AsyncHttpClient instance - and thus the default, shared CookieStore - to reach both an attacker-influenced host and a trusted host are impacted. This issue has been fixed in versions 2.16.0 and 3.0.11.

osv:DEBIAN-CVE-2026-55688

async-http-client

Fixed versions: 2.12.3-1+deb12u1

Complete source record
{
  "id": "74f38797b84a4672c7230058e9356ac26b0eccc8bd4da67a93e0fc049f72a887",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-55688",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2026-55688",
    "summary": "The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. In versions from 2.0.0 prior to 2.16.0 and from 3.0.0.Beta1 prior to 3.0.11, 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, leading to a cookie tossing / cookie injection issue. 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. Applications that use a single AsyncHttpClient instance - and thus the default, shared CookieStore - to reach both an attacker-influenced host and a trusted host are impacted. This issue has been fixed in versions 2.16.0 and 3.0.11.",
    "evidence": "osv:DEBIAN-CVE-2026-55688",
    "products": [
      {
        "name": {
          "value": "async-http-client",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.12.3-1+deb12u1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "2.12.3-1",
            "evidence": "/affected/0/versions"
          }
        ]
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "DEBIAN-CVE-2026-55688",
      "aliases": [
        "DEBIAN-CVE-2026-55688"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.12.3-1+deb12u1"
                }
              ]
            }
          ],
          "package": {
            "name": "async-http-client",
            "purl": "pkg:deb/debian/async-http-client?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "versions": [
            "2.12.3-1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-55688.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-26T11:47:34.571333461Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-55688"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2026-55688"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-55688",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 450929,
  "published_at": "2026-07-01T20:17:11.273+00:00"
}