The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. From 2.1.0 until 3.0.14, the enabled-by-default cookie store replaces a Cookie header explicitly supplied through setHeader or addHeader whenever the store contributes any cookie for the origin. In a shared client, stored cookies originating from one user can replace a different user's request cookie, causing the request to execute under the wrong session. This bypasses the earlier CVE-2024-53990 remediation, which covered cookies supplied through addCookie but not a directly supplied header. In the affected execution path, setHeader, addHeader, Cookie header, and CookieStore control or expose the vulnerable behavior. This issue is fixed in version 3.0.14.