CVE-2026-45300 is a high-severity (CVSS 7.4) Information Exposure vulnerability in org.asynchttpclient:async-http-client. O3 Security confirms whether CVE-2026-45300 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
async-http-client: Cookie header not stripped on cross-origin redirect
Real-World Exposure
org.asynchttpclient:async-http-client☕org.asynchttpclient:async-http-clientReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.asynchttpclient:async-http-client | ≥ 3.0.0.Beta1&&< 3.0.10 | 3.0.10 |
| ☕Maven | org.asynchttpclient:async-http-client | ≥ 2.0.0&&< 2.15.0 | 2.15.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.asynchttpclient:async-http-client. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update org.asynchttpclient:async-http-client to 3.0.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45300 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-45300 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-45300. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-45300 in your dependencies?
O3 detects CVE-2026-45300 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.