# CVE-2026-107227: AsyncHttpClient unbounded WebSocket decompression denial of service

Source: https://junglewise.ai/threats/cve-2026-107227-asynchttpclient-unbounded-websocket-permessage-deflate  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-08. Updated: 2026-10-08  
License: CC BY 4.0 with a link back

CVE-2026-107227 · Severity: high · CVSS 7.5 · Published 2026-10-08

AsyncHttpClient is a library for making HTTP and WebSocket requests from Java applications. When WebSocket compression is enabled, a malicious or compromised server can send a small compressed message that decompresses to gigabytes, exhausting the client's memory and causing the application to crash or become unresponsive. The vulnerability only affects applications that explicitly enable compression and connect to untrusted servers.

Technologies: [AsyncHttpClient](https://junglewise.ai/threats/technologies/asynchttpclient). Vendors: [AsyncHttpClient](https://junglewise.ai/threats/vendors/asynchttpclient).

## Quick answers

**Is CVE-2026-107227 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-107227 being exploited in the wild.

**How severe is CVE-2026-107227?** High severity, with a CVSS score of 7.5, published 8 October 2026.

**Which products and versions are affected?** AsyncHttpClient 2.2.0 through 2.16.1, 3.x through 3.0.13.

**Is there a fix for CVE-2026-107227?** Yes: fixed in 3.0.14. Until then: Leave WebSocket compression disabled, which is the default. Only enable `setEnableWebSocketCompression(true)` if connecting to trusted servers. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-107227 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-107227?** Check whether you run AsyncHttpClient at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 3.0.14

Leave WebSocket compression disabled, which is the default. Only enable `setEnableWebSocketCompression(true)` if connecting to trusted servers.

## Technical details

The vulnerability is an unbounded decompression issue in the WebSocket permessage-deflate handler. When compression is enabled, Netty's WebSocketClientCompressionHandler uses an unbounded inflater, and the frame size limits are enforced before decompression. A ~2 MiB compressed message can inflate to ~2 GiB, exhausting heap memory. This is fixed in AsyncHttpClient 3.0.14 by introducing a configurable `webSocketMaxDecompressedFrameSize` limit that defaults to 128 MiB.

## Affected products

- AsyncHttpClient AsyncHttpClient 2.2.0 through 2.16.1, 3.x through 3.0.13

## Identifiers

- CVE-2026-107227
- GHSA-x8v2-478q-2hvg

## Timeline

- 2026-10-08: advisory

## Related threats

- [AsyncHttpClient resumable download information disclosure and file tampering](https://junglewise.ai/threats/cve-2026-102740-the-asynchttpclient-library-allows-java-applications-to-execute)
- [AsyncHttpClient cookie security bypass in HTTP](https://junglewise.ai/threats/cve-2026-107226-asynchttpclient-cookies-received-over-plaintext-http-can-plant)
- [AsyncHttpClient CookieStore header override via setHeader](https://junglewise.ai/threats/cve-2026-107228-asynchttpclient-cookiestore-silently-overrides-caller-s-explicit)
- [AsyncHttpClient pooled connection reuse across NTLM and Negotiate logins](https://junglewise.ai/threats/cve-2026-107230-asynchttpclient-pooled-connections-can-still-be-shared-across)
- [AsyncHttpClient WebSocket proxy credentials sent to origin server](https://junglewise.ai/threats/cve-2026-107285-asynchttpclient-websocket-proxy-credentials-sent-to-the-origin)