vulnerability / NVI-00012179 / Revision 2
AsyncHttpClient: Unbounded WebSocket permessage-deflate decompression enables a decompression-bomb denial of service when compression is enabled
GitHub lists this reviewed advisory for org.asynchttpclient:async-http-client, org.asynchttpclient:async-http-client. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
7.5 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
7.5 HIGH (3.1)
security-advisories@github.com severity; no combined Null risk score.
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
org.asynchttpclient:async-http-client
source listed>= 3.0.0, <= 3.0.13
### Impact With WebSocket compression enabled, the client inflates `permessage-deflate` messages with no limit on the decompressed size. It installed Netty's shared `WebSocketClientCompressionHandler.INSTANCE`, whose inflater is unbounded, and `webSocketMaxFrameSize` and `webSocketMaxBufferSize` only bound the compressed bytes, because the frame aggregator sits in front of the inflater. A malicious or compromised WebSocket server, or anyone on the path of a `ws://` connection, can therefore send a message of about 2 MiB that inflates to about 2 GiB, the most a Netty buffer can hold. The client then copies the inflated message again to hand it to the listener. That exhausts the heap of a typically sized JVM. Netty catches the resulting `OutOfMemoryError` and closes that connection, but while the buffer is live any other allocation in the process can fail too, and a server that keeps sending such messages, on one connection or several, keeps the client at heap exhaustion. ### Who is Impacted Only applications that enable WebSocket compression with `setEnablewebSocketCompression(true)`, which is off by default, and connect to a WebSocket server that is untrusted, compromised, or r
org.asynchttpclient:async-http-client
source listed>= 2.2.0, <= 2.16.1
### Impact With WebSocket compression enabled, the client inflates `permessage-deflate` messages with no limit on the decompressed size. It installed Netty's shared `WebSocketClientCompressionHandler.INSTANCE`, whose inflater is unbounded, and `webSocketMaxFrameSize` and `webSocketMaxBufferSize` only bound the compressed bytes, because the frame aggregator sits in front of the inflater. A malicious or compromised WebSocket server, or anyone on the path of a `ws://` connection, can therefore send a message of about 2 MiB that inflates to about 2 GiB, the most a Netty buffer can hold. The client then copies the inflated message again to hand it to the listener. That exhausts the heap of a typically sized JVM. Netty catches the resulting `OutOfMemoryError` and closes that connection, but while the buffer is live any other allocation in the process can fail too, and a server that keeps sending such messages, on one connection or several, keeps the client at heap exhaustion. ### Who is Impacted Only applications that enable WebSocket compression with `setEnablewebSocketCompression(true)`, which is off by default, and connect to a WebSocket server that is untrusted, compromised, or r
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. NIST National Vulnerability Database
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
- NVD lastModified does not establish freshness of every associated CPE record.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-x8v2-478q-2hvg ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-107227 ↗
NIST National Vulnerability Database · official catalog
Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 2 ·
Source facts changed; compare the preserved prior revision.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.