AsyncHttpClient async-http-client up to 2.14.4/3.0.8 on Basic/Digest Header Authorization information disclosure

Summaryinfo

A vulnerability classified as problematic has been found in AsyncHttpClient async-http-client up to 2.14.4/3.0.8 on Basic/Digest. Affected by this issue is some unknown functionality of the component Header Handler. Performing a manipulation of the argument Authorization results in information disclosure. This vulnerability is identified as CVE-2026-40490. The attack can be initiated remotely. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in AsyncHttpClient async-http-client up to 2.14.4/3.0.8 on Basic/Digest. It has been classified as problematic. This affects some unknown processing of the component Header Handler. The manipulation of the argument Authorization with an unknown input leads to a information disclosure vulnerability. CWE is classifying the issue as CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. This is going to have an impact on confidentiality. The summary by CVE is:

The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. When redirect following is enabled (followRedirect(true)), versions of AsyncHttpClient prior to 3.0.9 and 2.14.5 forward Authorization and Proxy-Authorization headers along with Realm credentials to arbitrary redirect targets regardless of domain, scheme, or port changes. This leaks credentials on cross-domain redirects and HTTPS-to-HTTP downgrades. Additionally, even when stripAuthorizationOnRedirect is set to true, the Realm object containing plaintext credentials is still propagated to the redirect request, causing credential re-generation for Basic and Digest authentication schemes via NettyRequestFactory. An attacker who controls a redirect target (via open redirect, DNS rebinding, or MITM on HTTP) can capture Bearer tokens, Basic auth credentials, or any other Authorization header value. The fix in versions 3.0.9 and 2.14.5 automatically strips Authorization and Proxy-Authorization headers and clears Realm credentials whenever a redirect crosses origin boundaries (different scheme, host, or port) or downgrades from HTTPS to HTTP. For users unable to upgrade, set `(stripAuthorizationOnRedirect(true))` in the client config and avoid using Realm-based authentication with redirect following enabled. Note that `(stripAuthorizationOnRedirect(true))` alone is insufficient on versions prior to 3.0.9 and 2.14.5 because the Realm bypass still re-generates credentials. Alternatively, disable redirect following (`followRedirect(false)`) and handle redirects manually with origin validation.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-40490 since 04/13/2026. The exploitability is told to be difficult. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1592 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 307461 (Linux Distros Unpatched Vulnerability : CVE-2026-40490), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.14.5 or 3.0.9 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (307461). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• AsyncHttpClient

Name

• async-http-client

Version

• 2.14.0
• 2.14.1
• 2.14.2
• 2.14.3
• 2.14.4
• 3.0.0
• 3.0.1
• 3.0.2
• 3.0.3
• 3.0.4
• 3.0.5
• 3.0.6
• 3.0.7
• 3.0.8

License

• open-source

Website

• Product: https://github.com/AsyncHttpClient/async-http-client/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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