CVE-2026-107226 AsyncHttpClient CVE debrief

Who should care

Defenders responsible for applications using the AsyncHttpClient library, especially those handling sensitive cookie-based authentication or authorization, should assess exposure and prioritize verification and remediation efforts.

Why it matters

The AsyncHttpClient library fails to properly handle Secure cookies received over plaintext HTTP, allowing an attacker to plant, overwrite, or delete Secure cookies set over HTTPS. Defenders should prioritize verifying exposure and remediation efforts for applications using vulnerable versions of the library.

• An attacker can plant, overwrite, or delete Secure cookies set over HTTPS by sending a plaintext HTTP request with a Set-Cookie header.
• An attacker can exploit this vulnerability without being on the network path, as long as they can answer a plaintext request to the site.
• Defenders should verify exposure of AsyncHttpClient library usage in their environments, especially in applications handling sensitive cookie-based authentication or authorization.
• Remediation priority is high for applications using vulnerable versions of AsyncHttpClient library.

Technical summary

The AsyncHttpClient library fails to properly handle Secure cookies received over plaintext HTTP, allowing an attacker to plant, overwrite, or delete Secure cookies set over HTTPS. This vulnerability affects versions 2.1.0 to 2.16.1 and 3.0.0 to 3.0.13 of the org.asynchttpclient:async-http-client package. The issue arises from the cookie store ignoring the scheme a Set-Cookie arrived on and not implementing the rules for ignoring cookies with the Secure attribute unless they arrived over a secure connection. An attacker can exploit this vulnerability by sending a plaintext HTTP request with a Set-Cookie header, potentially allowing them to set, replace, or delete Secure cookies. Defenders should prioritize

Defensive priority

Defenders should prioritize verifying exposure of AsyncHttpClient library usage in their environments, especially in applications handling sensitive cookie-based authentication or authorization.

Recommended defensive actions

• Verify AsyncHttpClient library usage in environments, especially in applications handling sensitive cookie-based authentication or authorization.
• Check if applications using AsyncHttpClient library are exposed to this vulnerability by reviewing their dependency versions.
• Consider upgrading to version 3.0.14 or later of the org.asynchttpclient:async-http-client package.
• Monitor for potential cookie tampering attacks targeting applications using vulnerable versions of AsyncHttpClient library.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• 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 vulnerability is caused by the cookie store ignoring the scheme a Set-Cookie arrived on, and not implementing the rules for ignoring cookies with the Secure attribute unless they arrived over a secure connection. Evidence is based on the AsyncHttpClient library's behavior and the provided source item.

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.