PatchSiren cyber security CVE debrief

CVE-2026-45300 AsyncHttpClient CVE debrief

The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. Versions on the 2.x branch prior to 2.15.0 and the 3.x branch prior to 3.0.10 leak `Cookie` headers to cross-origin redirect targets. When following a redirect to a different origin, the `propagatedHeaders()` method in `Redirect30xInterceptor.java` strips `Authorization` and `Proxy-Authorization` headers but does not strip the `Cookie` header, causing session cookies and other sensitive cookie values to be sent to attacker-controlled servers. Versions 2.15.0 and 3.0.10 patch the issue.

Vendor: AsyncHttpClient
Product: async-http-client
CVSS: HIGH 7.4
CISA KEV: Not listed in stored evidence
Original CVE published: 2026-06-05
Original CVE updated: 2026-07-23
Advisory published: 2026-06-05
Advisory updated: 2026-07-23

Who should care

Users of AsyncHttpClient library versions 2.x prior to 2.15.0 and 3.x prior to 3.0.10 should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The AsyncHttpClient library has a vulnerability that allows `Cookie` headers to be leaked to cross-origin redirect targets. This can lead to sensitive cookie values being sent to attacker-controlled servers.

Defensive priority

HIGH

Recommended defensive actions

Upgrade to AsyncHttpClient library version 2.15.0 or later for 2.x branch
Upgrade to AsyncHttpClient library version 3.0.10 or later for 3.x branch

Evidence notes

The vulnerability was patched in versions 2.15.0 and 3.0.10 of the AsyncHttpClient library.

Sources and references

Verified primary and authoritative sources

CVE-2026-45300 CVE Program record
Publisher, destination, and source semantics verified

URL: https://www.cve.org/CVERecord?id=CVE-2026-45300

CVE Program - Official CVE Program record with source-provided CVE metadata.
CVE-2026-45300 NVD vulnerability detail
Publisher, destination, and source semantics verified

URL: https://nvd.nist.gov/vuln/detail/CVE-2026-45300

NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Mitigation or vendor reference
Unverified legacy reference

URL: https://github.com/AsyncHttpClient/async-http-client/commit/3b0e3e9e

[email protected] - Patch
Mitigation or vendor reference
Unverified legacy reference

URL: https://github.com/AsyncHttpClient/async-http-client/releases/tag/async-http-client-project-3.0.10

[email protected] - Product, Release Notes
Mitigation or vendor reference
Unverified legacy reference

URL: https://github.com/AsyncHttpClient/async-http-client/security/advisories/GHSA-fmxf-pm6p-7xgm

[email protected] - Exploit, Mitigation, Patch, Vendor Advisory

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.