# CVE-2026-85720: AsyncHttpClient: Origin credentials sent to the proxy on the plaintext CONNECT request

> Attackers can intercept origin credentials sent in plaintext during proxy CONNECT requests, exposing sensitive authentication data to proxies and network observers.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 21 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-85720, ECHO-085c-5da2-0e78, GHSA-xr57-gcx8-52hf, MINI-76xm-5pmc-73pp, MINI-77qw-pcch-mrr4, MINI-jfr8-2v76-mx22, MINI-pw44-32pc-88qr, UBUNTU-CVE-2026-85720

## What is CVE-2026-85720?

CVE-2026-85720 is a medium-severity vulnerability in AsyncHttpClient async-http-client, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### 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.

Weakness: CWE-522 (Insufficiently Protected Credentials), CWE-319 (Cleartext Transmission of Sensitive Information)

## Which versions are affected by CVE-2026-85720?

4 open source packages ship an affected version, including org.asynchttpclient:async-http-client.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `org.asynchttpclient:async-http-client` | Maven | From 2.0.0 | 2.16.1 |
| `org.asynchttpclient:async-http-client` | Maven | From 2.0.0 | 2.16.1 |
| `org.asynchttpclient:async-http-client` | Maven | From 3.0.0 | 3.0.12 |
| `org.asynchttpclient:async-http-client` | Maven | From 3.0.0 | 3.0.12 |

## How do I fix CVE-2026-85720?

Upgrade org.asynchttpclient:async-http-client to a fixed version for your release line: 2.16.1 or 3.0.12.

## Is CVE-2026-85720 being exploited?

There is no known exploitation of CVE-2026-85720 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-85720 and fix it if it is affected.

What it is: CVE-2026-85720 is a medium-severity vulnerability in AsyncHttpClient async-http-client, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-85720 in the wild and no public exploit code.

Affected packages and fixed versions:
- org.asynchttpclient:async-http-client (Maven): affected from 2.0.0; fixed in 2.16.1
- org.asynchttpclient:async-http-client (Maven): affected from 2.0.0; fixed in 2.16.1
- org.asynchttpclient:async-http-client (Maven): affected from 3.0.0; fixed in 3.0.12
- org.asynchttpclient:async-http-client (Maven): affected from 3.0.0; fixed in 3.0.12

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-85720/ (Markdown: https://insights.sbomify.com/CVE-2026-85720/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-85720
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-85720
- OSV: https://osv.dev/vulnerability/CVE-2026-85720

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-85720/
Summaries are generated and may contain mistakes; the official description above is the record.