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

Quick assessment

Affected
AsyncHttpClient async-http-client
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

AsyncHttpClient（AHC）库使 Java 应用程序能够轻松地执行 HTTP 请求并异步处理 HTTP 响应。从 3.0.8 到 3.0.12 版本中，当客户端的 或 设置为大于零时，如果在 TLS 握手完成前连接建立失败，每次失败都会导致一个连接许可（connection permit）泄漏。NettyConnectListener 在绑定所有失败路径到通道的 之前，就会从 中移除 许可，因此在某些中止场景下，许可可能未被释放。反复出现的失败可能导致：在每主机连接限制下永久性地锁定某个主机，或在全局连

CVSS 5.9 · Medium
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I. Basic Information for CVE-2026-85718

Vulnerability Information
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Vulnerability Title
AsyncHttpClient: Connection permit leak on TLS handshake failure causes per-host denial of service
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
AsyncHttpClient async-http-client >= 3.0.8, < 3.0.12 -

II. Public POCs for CVE-2026-85718

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III. Intelligence Information for CVE-2026-85718

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Patches & Fixes for CVE-2026-85718 (3)

Vendor Advisories for CVE-2026-85718 (1)

Same Patch Batch · AsyncHttpClient · 2026-09-17 · 6 CVEs total

CVE-2026-85719 7.5 HIGH AsyncHttpClient: SOCKS proxy credentials sent to the origin server over plaintext HTTP
CVE-2026-85721 7.5 HIGH AsyncHttpClient: Unbounded HTTP/1.1 response decompression enables a decompression-bomb de
CVE-2026-85717 6.8 MEDIUM AsyncHttpClient: Client-wide realm credentials re-sent to a cross-origin redirect target
CVE-2026-85720 5.9 MEDIUM AsyncHttpClient: Origin credentials sent to the proxy on the plaintext CONNECT request
CVE-2026-85716 3.7 LOW AsyncHttpClient: SCRAM and Digest mutual-authentication responses are not verified

IV. Related Vulnerabilities

Same product: async-http-client
Same vendor: AsyncHttpClient
Same weakness: CWE-400

V. Comments for CVE-2026-85718

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