CVE-2026-107284: Asynchttpclient Async-HTTP-Client

Low severity, CVSS 3.7. EPSS: 0.1% chance of exploitation in the next 30 days.

The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. Prior to 3.0.12 and 2.16.1, WebSocketHandler.upgrade aborts a handshake whose Sec-WebSocket-Accept value is missing or invalid but continues into pipeline installation and onOpen delivery. Frames coalesced with the invalid 101 response can be decoded and delivered from a peer that did not prove the handshake, although the request future fails and the channel closes. This issue is fixed in versions 3.0.12 and 2.16.1.

Affected products

• Asynchttpclient Async-HTTP-Client: from 3.0.0, before 3.0.12 (fixed in 3.0.12); from 2.0.0, before 2.16.1 (fixed in 2.16.1)

Published 2026-10-07. Last modified 2026-10-08.