EUVD-2026-81909
GHSA-xr57-gcx8-52hf
Severity by source
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Automatic cleartext disclosure needs no attacker auth (PR:N) but only occurs under a specific proxy+preemptive-auth config with an on-path observer (AC:H); confidentiality-only credential leak (C:H, I/A:N).
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
Lifecycle Timeline
2DescriptionCVE.org
The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. From 2.0.0 until 2.16.1 and 3.0.12, a request using an HTTP proxy to reach an HTTPS origin can expose preemptive origin credentials because NettyRequestFactory and NettyRequestSender.sendRequestWithNewChannel attach Authorization to the plaintext CONNECT request before the TLS tunnel exists. Basic or Digest credentials and per-connection NTLM, Kerberos, or SPNEGO tokens intended for the origin are therefore visible to the proxy and to observers on the client-to-proxy hop. The tunneled request still receives origin Authorization after the tunnel is established, while Proxy-Authorization remains on CONNECT for its intended proxy recipient. This issue is fixed in versions 2.16.1 and 3.0.12.
AnalysisAI
Cleartext exposure of origin credentials in AsyncHttpClient (AHC) 2.0.0-2.16.0 and 3.0.0-3.0.11 occurs when a Java application reaches an HTTPS origin through an HTTP CONNECT proxy while using preemptive origin authentication: the library attaches the origin's Authorization header - Basic or Digest credentials, plus per-connection NTLM/Kerberos/SPNEGO tokens - to the plaintext CONNECT request before any TLS tunnel exists, so the proxy and any observer on the client-to-proxy hop can read credentials meant only for the origin. The vulnerability is rated CVSS 5.9 (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N) with high confidentiality impact but a high attack-complexity qualifier, because exploitation requires the specific non-default combination of a CONNECT proxy, preemptive origin authentication, and an adversary positioned on that network segment; authentication requirements are not confirmed from the supplied vector beyond PR:N, and there is no public exploit identified at time of analysis. …
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Vulnerability AssessmentAI
| Exploitation | Exploitation requires a very specific deployment: an application using AsyncHttpClient 2.0.0-2.16.0 or 3.0.0-3.0.11 that reaches an HTTPS origin through an HTTP CONNECT proxy AND uses preemptive origin authentication - Basic/Digest credentials or a per-connection NTLM/Kerberos/SPNEGO token intended for the origin. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | This is a moderate, information-disclosure flaw rather than a critical priority. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Vendor-released patch: AsyncHttpClient 2.16.1 (2.x line) and 3.0.12 (3.x line) fix this issue by removing the origin Authorization header and the per-connection NTLM/Kerberos/SPNEGO token from the plaintext CONNECT; upgrade to the highest available release on your line, and on 3.x prefer 3.0.13 rather than stopping at 3.0.12, because 3.0.12 is itself affected by a separate issue, GHSA-rqf5-2wxv-rjf4, in which a Digest challenge the client cannot read downgrades to Basic and sends the password in cleartext. … Detailed patch versions, workarounds, and compensating controls in full report. |
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