Sensitive cookie with improper SameSite attribute in Async-http-client - CVE-2026-55688
Published: June 16, 2026
Vulnerability identifier: #VU134579
CSH Severity: Low
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-55688
CWE-ID: CWE-1275
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to manipulate cookies for an unrelated domain.
The vulnerability exists due to improper cookie domain validation in ThreadSafeCookieStore when storing cookies from HTTP responses. A remote attacker can cause the client to connect to an attacker-influenced host that sets a crafted cookie to manipulate cookies for an unrelated domain.
Applications are exposed when a single AsyncHttpClient instance shares its cookie store across both attacker-influenced and trusted hosts, such as when following redirects or fetching user-supplied URLs.
Affected software
Async-http-client
How to mitigate CVE-2026-55688
Install security update from vendor's website.
Async-http-client - addressed in versions 2.16.0, 3.0.11