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CVE-2026-59903 affects the HTTP CORS handler in Netty's io.netty:netty-codec-http component before the fixed releases 4.1.137.Final and 4.2.17.Final. CorsHandler.setVaryHeader replaces application-defined Vary headers, including Authorization or Cookie, with Origin instead of preserving the existing cache-variation requirements. In applications behind caching proxies or CDNs, this can cause authenticated or user-specific responses to be reused across users, resulting in cache poisoning and disclosure of sensitive information.
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14 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A high-severity information-disclosure vulnerability in Netty's HTTP codec. CorsHandler overwrites application Vary headers with Origin, potentially causing caching proxies or CDNs to serve authenticated responses to other users. The reported CVSS v3 base score is 7.5. Fixes are available in versions 4.1.137.Final and 4.2.17.Final.
Unknown
A medium-severity Netty HTTP CORS handler flaw in which CorsHandler's setVaryHeader can overwrite application Vary headers with Origin, potentially allowing caching proxies or CDNs to serve authenticated responses to other users and disclose sensitive data.
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Cross-references every affected SKU, including bundled OEM variants.
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