Medium [CVE-2026-59903] Information disclosure via CORS Vary header overwrite
This medium-severity Red Hat Linux advisory covers CVE-2026-59903 affecting Red Hat build of Quarkus, Red Hat Ceph Storage 6, Red Hat Ceph Storage 7.
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Summary
Netty is an asynchronous, event-driven network application framework. Prior to 4.1.137.Final and 4.2.17.Final, io.netty.handler.codec.http.cors.
CorsHandler setVaryHeader replaces application Vary headers such as Authorization or Cookie with Origin, allowing a caching proxy or CDN to reuse authenticated responses across users and disclose sensitive information.
This Moderate impact information disclosure flaw in Netty arises from the `CorsHandler` incorrectly overwriting application `Vary` headers with `Origin`. This could allow caching proxies or CDNs to reuse authenticated responses across different users, potentially exposing sensitive data.
Exploitation requires the presence of a caching proxy or CDN in front of the affected Netty application. Red Hat severity: Moderate — CVSS 6.5 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N).
Weakness: CWE-444. Affected Red Hat products: Red Hat build of Quarkus; Red Hat Ceph Storage 6; Red Hat Ceph Storage 7; Red Hat Ceph Storage 8; Red Hat Ceph Storage 9; Red Hat Enterprise Linux AI (RHEL AI) 3; Red Hat Offline Knowledge Portal; Red Hat OpenShift AI (RHOAI); Red Hat OpenShift Dev Spaces; Red Hat Satellite 6.
- < 4.1.137.Final
- < 4.2.17.Final
Official advisory · high-confidence parse· fetched 3 hours ago·verify at source
- 4.1.137
- 4.2.17
Official advisory · high-confidence parse· fetched 3 hours ago·verify at source
Mitigation checklist
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Official advisory · high-confidence parse· fetched 3 hours ago·verify at source
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