CVE-2026-15075 in Eclipse Vert.x
In Eclipse Vert.x versions up to and including 4.5.29 (4.x branch) and 5.1.4 (5.x branch), DefaultRedirectHandler (vertx-core) propagates all request headers as-is across cross-origin HTTP 30x redirects. Only Content-Length is stripped; no origin comparison (scheme, host, port) is performed before copying headers to the redirect target. As a result, credential headers, including Authorization, Cookie, Proxy-Authorization, and arbitrary custom headers such as X-API-Token, are forwarded to the redirect destination without the caller's knowledge. An attacker who can cause a Vert.x HttpClient to issue a request that is redirected to an attacker-controlled host (for example, by supplying a URL to a webhook dispatcher, image proxy, or microservice URL fetcher) can capture bearer tokens, basic-auth credentials, session cookies, and API keys attached to the original request.
Quick answer
Eclipse Foundation Eclipse Vert.x should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- Eclipse Vert.x 4.x through 4.5.29
- Eclipse Vert.x 5.x through 5.1.4
Fixed versions
- Eclipse Vert.x 4.5.30 or later
- Eclipse Vert.x 5.1.5 or later
How to fix it
CVE-2026-15075 affects Eclipse Vert.x. In simple terms, a user may get access to data or actions they should not have. Fix it by updating to Eclipse Vert.x 4.5.30 or later; Eclipse Vert.x 5.1.5 or later. If this system is online or used by admins, treat the fix as important.
- Find every place where Eclipse Vert.x is installed or used.
- Check if the version matches: Eclipse Vert.x 4.x through 4.5.29; Eclipse Vert.x 5.x through 5.1.4.
- Update or apply the vendor fix: Eclipse Vert.x 4.5.30 or later; Eclipse Vert.x 5.1.5 or later.
- If you cannot update today, allow only trusted users and trusted networks.
- Turn off the affected feature or plugin if the vendor says that is safe to do.
- Check logs for crashes, strange requests, new admin actions, or unexpected access.
- Change secrets or passwords if you think data or admin access may have been exposed.
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Verify the fix
- Confirm the installed version or mitigation matches: Eclipse Vert.x 4.5.30 or later; Eclipse Vert.x 5.1.5 or later.
- Confirm the affected feature is no longer exposed to untrusted users.
- Run the affected workflow again and make sure it still works.
- Review logs again after the fix for repeated suspicious activity.
- Run a new Fixnx scan if this software is part of a public website.
- Save the advisory link and proof of the fix in your change record.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-15075?
Eclipse Foundation Eclipse Vert.x versions listed as affected should be reviewed: Eclipse Vert.x 4.x through 4.5.29, Eclipse Vert.x 5.x through 5.1.4.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.