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Vulnerability · Published Sep 17, 2026 · Assigned by GitHub_M

CVE-2026-85718AsyncHttpClient: Connection permit leak on TLS handshake failure causes per-host denial of service

Medium 5.9

In plain English

A medium-severity uncontrolled resource consumption 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 0.5% (higher than 45% of all known vulnerabilities).

Severity (CVSS 3.1)5.9Medium
Exploit odds (30 days)0.5%top 54.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. From 3.0.8 until 3.0.12, a client with maxConnections or maxConnectionsPerHost set above zero leaks one connection permit whenever TLS connection establishment fails before the handshake completes. NettyConnectListener removes the partitionKeyLock permit from NettyResponseFuture before every failure path is bound to the channel closeFuture, so an abort can leave the permit unreleased. Repeated failures can permanently lock out one host under a per-host limit or drain the shared pool under a global limit, blocking later requests even when no connection remains open. The default unlimited connection setting is not affected. This issue is fixed in version 3.0.12.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Ubuntu:22.04:LTSasync-http-clientno fix listedUBUNTU-CVE-2026-85718
Ubuntu:24.04:LTSasync-http-clientno fix listedUBUNTU-CVE-2026-85718
Ubuntu:26.04:LTSasync-http-clientno fix listedUBUNTU-CVE-2026-85718
Ubuntu:26.10async-http-clientno fix listedUBUNTU-CVE-2026-85718

Affected products (as reported)

VendorProductVersions
AsyncHttpClient async-http-client >= 3.0.8, < 3.0.12

Weakness: CWE-400, CWE-772 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

References