CVE-2026-107227 AsyncHttpClient CVE debrief

Who should care

Defenders responsible for Java applications using AsyncHttpClient for WebSocket communication should assess their exposure and prioritize updating to version 3.0.14 or later. This includes operators, platform administrators, vulnerability management teams, and security teams who need to ensure that systems are updated and monitored for potential exposure to this vulnerability. Additionally, defenders should review compensating controls for exposed systems,

Why it matters

The AsyncHttpClient library has a vulnerability that allows for unbounded WebSocket permessage-deflate decompression, potentially leading to DoS attacks. Defenders should prioritize updating to version 3.0.14 or later and assess systems using AsyncHttpClient for exposure.

• Potential for denial-of-service (DoS) attacks through decompression bombs
• Exhaustion of JVM heap due to large Netty buffers

Technical summary

The AsyncHttpClient library, used for executing HTTP requests and processing responses in Java applications, has a vulnerability in versions 2.2.0 through 3.0.14. This issue allows for unbounded WebSocket permessage-deflate decompression when compression is enabled, potentially leading to a denial-of-service (DoS) attack through a decompression bomb. A malicious WebSocket peer can exploit this by sending a small compressed message that expands to a large Netty buffer, exhausting the JVM heap. The issue is addressed in version 3.0.14. Defenders should prioritize updating to version 3.0.14 or later to mitigate this vulnerability. Systems using AsyncHttpClient for WebSocket communication should be assessed for 3.0

Defensive priority

Defenders should prioritize updating to version 3.0.14 or later to mitigate this vulnerability. Systems using AsyncHttpClient for WebSocket communication should be assessed for exposure, especially if they handle untrusted WebSocket connections.

Recommended defensive actions

• Update AsyncHttpClient to version 3.0.14 or later
• Assess systems using AsyncHttpClient for WebSocket communication for exposure
• Monitor for unusual WebSocket traffic patterns
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability, its impact, and the fix. However, specific details about exploitation or victim organizations are not provided, limiting the depth of the analysis.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.