Vulnerability · Published Sep 17, 2026 · Assigned by GitHub_M
CVE-2026-85720AsyncHttpClient: Origin credentials sent to the proxy on the plaintext CONNECT request
Medium 5.9
In plain English
A medium-severity security flaw in async-http-client from AsyncHttpClient. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 18% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | async-http-client | no fix listed | DEBIAN-CVE-2026-85720 |
| Maven | org.asynchttpclient:async-http-client | 2.16.1 | GHSA-xr57-gcx8-52hf |
| Maven | org.asynchttpclient:async-http-client | 3.0.12 | GHSA-xr57-gcx8-52hf |
| Ubuntu:22.04:LTS | async-http-client | no fix listed | UBUNTU-CVE-2026-85720 |
| Ubuntu:24.04:LTS | async-http-client | no fix listed | UBUNTU-CVE-2026-85720 |
| Ubuntu:26.04:LTS | async-http-client | no fix listed | UBUNTU-CVE-2026-85720 |
| Ubuntu:26.10 | async-http-client | no fix listed | UBUNTU-CVE-2026-85720 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| AsyncHttpClient | async-http-client | >= 2.0.0, < 2.16.1>= 3.0.0, < 3.0.12 |
Weakness: CWE-319, CWE-522 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
References
- https://github.com/AsyncHttpClient/async-http-client/security/advisories/GHSA-xr57-gcx8-52hf x_refsource_CONFIRM
- https://github.com/AsyncHttpClient/async-http-client/pull/2234 x_refsource_MISC
- https://github.com/AsyncHttpClient/async-http-client/commit/9dba5ac988b7e750551f59b2eab550b60ac8a0d6 x_refsource_MISC
- https://github.com/AsyncHttpClient/async-http-client/commit/d07dbc79f5cf378f63c246f6101d7579ace55acc x_refsource_MISC