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Vulnerability record · CVE-2026-59903 · published 17 August 2026

CVE-2026-59903: Netty vulnerability

Netty · Netty

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 issue is fixed in versions 4.1.137.Final and 4.2.17.Final.

7.5 CVSS 3.1 High EPSS 0.25% · top 85.8% CWE-524 · CWE-524
7.5CVSS 3.1 base score
0.25%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
5References
23 Sep 2026Last modified by NVD

Description

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 issue is fixed in versions 4.1.137.Final and 4.2.17.Final.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/netty/netty/pull/17213 Issue TrackingPatch
https://github.com/netty/netty/pull/17217 Issue TrackingPatch
https://github.com/netty/netty/releases/tag/netty-4.1.137.Final Release Notes
https://github.com/netty/netty/releases/tag/netty-4.2.17.Final Release Notes
https://github.com/netty/netty/security/advisories/GHSA-8c42-7qj2-3j46 Vendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-59903), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.