Cleartext transmission of sensitive information in Async-http-client - #VU142451
Published: August 13, 2026
Vulnerability identifier: #VU142451
CSH Severity: Medium
CVSS v4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-319
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to cleartext transmission of sensitive information in the HTTP CONNECT tunnel setup in Async-http-client when sending requests through an HTTP proxy to an HTTPS origin with preemptive origin authentication. A remote attacker can observe a plaintext CONNECT request carrying origin credentials or authentication tokens to disclose sensitive information.
The issue affects Basic credentials as well as NTLM, SPNEGO, and Kerberos tokens on the client-to-proxy hop before TLS is established.
Affected software
Async-http-client
Remediation
Install security update from vendor's website.
Async-http-client - addressed in versions 2.16.1, 3.0.12