Vulnerability · Published Jul 1, 2026 · Assigned by GitHub_M
CVE-2026-55688AsyncHttpClient: Cookie stored for an unrelated domain (cookie tossing) via ThreadSafeCookieStore
Medium 4.0
In plain English
A medium-severity security flaw in async-http-client from AsyncHttpClient. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 26% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | async-http-client | 2.12.3-1+deb12u1 | DEBIAN-CVE-2026-55688 |
| Maven | org.asynchttpclient:async-http-client | 3.0.11 | GHSA-m452-q8c9-rg2f |
| Maven | org.asynchttpclient:async-http-client | 2.16.0 | GHSA-m452-q8c9-rg2f |
| Ubuntu:22.04:LTS | async-http-client | 2.12.3-1ubuntu0.22.04.1 | USN-8655-1 |
| Ubuntu:22.04:LTS | async-http-client | 2.12.3-1ubuntu0.22.04.1 | UBUNTU-CVE-2026-55688 |
| Ubuntu:24.04:LTS | async-http-client | 2.12.3-1ubuntu0.24.04.1 | UBUNTU-CVE-2026-55688 |
| Ubuntu:24.04:LTS | async-http-client | 2.12.3-1ubuntu0.24.04.1 | USN-8655-1 |
| Ubuntu:25.10 | async-http-client | no fix listed | UBUNTU-CVE-2026-55688 |
| Ubuntu:26.04:LTS | async-http-client | 2.12.3-1ubuntu1.1 | USN-8655-1 |
| Ubuntu:26.04:LTS | async-http-client | 2.12.3-1ubuntu1.1 | UBUNTU-CVE-2026-55688 |
| Ubuntu:26.10 | async-http-client | no fix listed | UBUNTU-CVE-2026-55688 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| AsyncHttpClient | async-http-client | >= 2.0.0, < 2.16.0>= 3.0.0.Beta1, < 3.0.11 |
Weakness: CWE-1275 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N