AsyncHttpClient: WebSocket proxy credentials sent to the origin server over a CONNECT tunnel

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

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The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. Prior to 3.0.12 and 2.16.1, a proxied ws request is carried through CONNECT, but NettyRequestFactory.newNettyRequest and requestUri decide whether to attach proxy authentication and an absolute-form target only from whether the URI is secure. Because ws is not marked secure, the tunneled WebSocket upgrade sent to the origin includes the proxy's Proxy-Authorization value. Basic credentials are directly recoverable and Digest responses can be replayed or cracked offline. This issue is fixed in versions 3.0.12 and 2.16.1.

Source published

7 Oct 2026 21:28:34 UTC

Source modified

8 Oct 2026 17:57:33 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N