AsyncHttpClient sends origin credentials to the proxy on the plaintext CONNECT request

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-85720: 0.27% estimated exploitation activity in the next 30 days; percentile 18.46 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact When a request uses an HTTP proxy to reach an HTTPS origin, the client opens the tunnel with a plaintext CONNECT sent to the proxy before any TLS exists. On affected versions the origin's preemptive credentials were added to that CONNECT. A Basic realm sent Authorization: Basic base64(user:pass) to the proxy in the clear, and NTLM, SPNEGO or Kerberos realms sent their token. The proxy, and anyone who can read the client to proxy hop, saw credentials that were meant only for the origin. Affected versions 3.x: up to and including 3.0.11 2.x: up to and including 2.16.0 Patches Fixed in 3.0.12 on the 3.x line and in 2.16.1 on the 2.x line. The origin Basic or Digest Authorization is no longer put on the CONNECT; it is added to the tunnelled request once the tunnel is up. The per-connection NTLM, Kerberos and SPNEGO token is likewise no longer attached on the tunnel path; it never reached the origin there in any case, and the challenge flow still negotiates it inside the tunnel.…

Published by the source

17 Sep 2026, 17:19 UTC

Last modified by the source

17 Sep 2026, 17:30 UTC

Source last checked

26 Oct 2026, 16:55 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-xr57-gcx8-52hf

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-xr57-gcx8-52hf

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# Patch Next advisory brief: CVE-2026-85720

Advisory: AsyncHttpClient sends origin credentials to the proxy on the plaintext CONNECT request
IDs: CVE-2026-85720, GHSA-xr57-gcx8-52hf
Record: https://patchnext.com/advisories/cve-2026-85720 (revision 2, source checked 26 Oct 2026, 16:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.asynchttpclient:async-http-client 3.0.12, 2.16.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.asynchttpclient:async-http-client: affected >= 3.0.0, <= 3.0.11; >= 2.0.0, <= 2.16.0; fixed in 2.16.1, 3.0.12

## Suggested inspection (read-only)
- Maven org.asynchttpclient:async-http-client: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.asynchttpclient:async-http-client.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-xr57-gcx8-52hf (OSV record GHSA-xr57-gcx8-52hf lists affected ranges: Maven org.asynchttpclient:async-http-client >=3.0.0 =2.0.0 <2.16.1 (fixed))
- Verified: https://github.com/advisories/GHSA-xr57-gcx8-52hf (GitHub-reviewed advisory GHSA-xr57-gcx8-52hf lists affected ranges: Maven org.asynchttpclient:async-http-client >=3.0.0 =2.0.0 <=2.16.0)

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