CVE-2026-85718

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

MEDIUM
5.9
CVSS Score
Published: September 17, 2026 at 03:58 PM UTC
Updated: September 30, 2026 at 05:43 PM UTC
1 product affected across 1 vendorAsyncHttpClient

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Severity
MEDIUM5.9
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 3.0.12
Affected range stops below 3.0.12, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.9MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-400CWE-772

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