Resource exhaustion in Asynchttpclient Async-Http-Client
CVE-2026-85718
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.
Vulnerability class: DoS (Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.005 (45.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 45th percentile — 45.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Asynchttpclient Async-Http-Client — versions >= 3.0.8, < 3.0.12
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-85718?
- CVE-2026-85718 is a medium-severity vulnerability in Asynchttpclient Async-Http-Client, classified under Uncontrolled Resource Consumption. CVSS score: 5.9/10. Published 2026-09-17.
- How severe is CVE-2026-85718?
- Medium severity. CVSS v3 base score is 5.9 out of 10.