ZDF
Sign inSign up

Vulnerabilities

Vulnerability · CVE-2026-107227

AsyncHttpClient: Unbounded WebSocket permessage-deflate decompression enables a decompression-bomb denial of service when compression is enabled

Published Oct 8, 2026 · catalog updated Oct 8, 2026 · AsyncHttpClient: Unbounded WebSocket permessage-deflate

Check if you run it

No confirmed exploitation is on record for CVE-2026-107227. EPSS is 0.43%. Act only if a listed version of AsyncHttpClient: Unbounded WebSocket permessage-deflate is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (AsyncHttpClient: Unbounded WebSocket permessage-deflate).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.43%
Remediation
Advisory link
Affected products
Maven org.asynchttpclient:async-http-client

### Impact With WebSocket compression enabled, the client inflates messages with no limit on the decompressed size. It installed Netty's shared , whose inflater is unbounded, and and 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 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 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 , which is off by default, and connect to a WebSocket server that is untrusted, compromised, or reached over cleartext . ### Affected versions * 3.x: up to and including 3.0.13 * 2.x: from 2.2.0, when WebSocket compression was added, up to and including 2.16.1 ### Patches Fixed in 3.0.14. A new setting, ( , or the property), bounds how far a message may inflate, and a message that would go past it fails the connection. It defaults to 128000000 bytes, the same as , so a message is bounded alike whether or not it was compressed; a compressed message that inflates past that, which was accepted before, now fails the connection. With turned off, the bound applies to each frame instead, and fragments are delivered one at a time. Set it lower if you enable compression and do not expect large messages. disables the limit. The 2.x line is end of life and will not receive a fix. Upgrade to 3.0.14. ### Workarounds Leave WebSocket compression disabled, which is the default. ### Details After the handshake the inbound pipeline is , , , : the aggregator, which enforces , sees

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Maven org.asynchttpclient:async-http-client2.10.0, 2.10.1, 2.10.2
  • Maven org.asynchttpclient:async-http-client2.2.0 → 2.16.1
  • Maven org.asynchttpclient:async-http-client3.0.0 → 3.0.14

How to fix CVE-2026-107227

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-107227. EPSS is 0.43%. Act only if a listed version of AsyncHttpClient: Unbounded WebSocket permessage-deflate is installed.

Which versions are affected?

Compare what you have installed with 2.10.0, 2.10.1, 2.10.2, 2.2.0 → 2.16.1, 3.0.0 → 3.0.14. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-400: Uncontrolled Resource Consumption; CWE-409. EPSS 0.43%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 8, 2026 · Catalog

    Detected

    ### Impact With WebSocket compression enabled, the client inflates messages with no limit on the decompressed size. It installed Netty's shared , whose inflater is unbounded, and and 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 connection, can therefore send a message of about 2

  2. Oct 8, 2026 · Catalog

    Fix available

    Maven org.asynchttpclient:async-http-client 3.0.0 → 3.0.14

  3. Oct 8, 2026 · GitHub Advisory Database

    Fix available

    org.asynchttpclient:async-http-client fixed in 3.0.14

  4. Oct 8, 2026 · GitHub Advisory Database

    Fix available

    org.asynchttpclient:async-http-client fixed in 3.0.14

  5. Oct 8, 2026 · GitHub Advisory Database

    Fix available

    org.asynchttpclient:async-http-client fixed in 2.16.1

  6. Oct 8, 2026 · Catalog

    Updated

    ### Impact With WebSocket compression enabled, the client inflates messages with no limit on the decompressed size. It installed Netty's shared , whose inflater is unbounded, and and 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 connection, can therefore send a message of about 2

Sources

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.