Async Http Client up to 3.0.11 TLS Connection Establishment NettyConnectListener maxConnections/maxConnectionsPerHost resource consumption

Summaryinfo

A vulnerability labeled as problematic has been found in Async Http Client up to 3.0.11. Affected by this issue is the function NettyConnectListener of the component TLS Connection Establishment. Executing a manipulation of the argument maxConnections/maxConnectionsPerHost can lead to resource consumption. This vulnerability appears as CVE-2026-85718. The attack may be performed from remote. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Async Http Client up to 3.0.11. It has been declared as problematic. This vulnerability affects the function NettyConnectListener of the component TLS Connection Establishment. The manipulation of the argument maxConnections/maxConnectionsPerHost with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. As an impact it is known to affect availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-85718 since 09/04/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 3.0.12 eliminates this vulnerability.

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Productinfo

Name

• Async Http Client

Version

• 3.0.0
• 3.0.1
• 3.0.2
• 3.0.3
• 3.0.4
• 3.0.5
• 3.0.6
• 3.0.7
• 3.0.8
• 3.0.9
• 3.0.10
• 3.0.11

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CPE 2.2info

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