CVE-2026-55688
MediumCVSS 4.0Exploitation Probability (EPSS)
Low risk8th percentile — higher than 8% of all known CVEs
Summary
The AsyncHttpClient (AHC) library versions 2.0.0 through 2.15.0 and 3.0.0.Beta1 through 3.0.10 have a vulnerability in ThreadSafeCookieStore that does not verify whether the responding host is allowed to set a cookie for a domain. This allows an attacker-controlled host to inject a cookie for an unrelated domain, which the client then sends to that domain.
Risk Assessment
The organization risks that an application using a single AHC instance to communicate with both a trusted and an attacker-influenced host may send manipulated cookies to the trusted domain, potentially leading to session hijacking or data theft.
Recommendation
Immediately update the AsyncHttpClient library to version 2.16.0 or 3.0.11, which contain the fix for this vulnerability.
Original NVD description (English source)
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.