The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. Prior to 3.0.13 and 2.16.1, ThreadSafeCookieStore validates Domain attributes with domain matching but does not reject public suffixes. A host beneath a suffix such as co.uk can set a cookie for that suffix, after which the shared cookie store sends it to unrelated hosts under the suffix. This can inject or overwrite session-relevant cookie values across origins. This issue is fixed in versions 3.0.13 and 2.16.1.