# CVE-2026-59903: Netty: Cache Poisoning and Information Disclosure via CORS Vary Header Overwrite

> CVE-2026-59903: Netty: Cache Poisoning and Information Disclosure via CORS Vary Header Overwrite. CVSS 6.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-59903
Last updated: 2026-09-23T15:21:27Z

- Published: 2026-08-17 17:56 UTC · Updated: 2026-09-23 15:21 UTC · Assigner: GitHub\_M
- CVSS: 6.5 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N
- EPSS: 0.32%, 25th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-524

## 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.

## Affected vendors and products

- netty: netty

## Tracked companies

- [Jira](https://rewindex.com/company/jira.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-59903)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-59903)
- [https://github.com/netty/netty/pull/17213](https://github.com/netty/netty/pull/17213)
- [https://github.com/netty/netty/pull/17217](https://github.com/netty/netty/pull/17217)
- [https://github.com/netty/netty/releases/tag/netty-4.1.137.Final](https://github.com/netty/netty/releases/tag/netty-4.1.137.Final)
- [https://github.com/netty/netty/releases/tag/netty-4.2.17.Final](https://github.com/netty/netty/releases/tag/netty-4.2.17.Final)
- [https://github.com/netty/netty/security/advisories/GHSA-8c42-7qj2-3j46](https://github.com/netty/netty/security/advisories/GHSA-8c42-7qj2-3j46)

---

_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


---
Canonical: https://rewindex.com/cve/CVE-2026-59903 · Markdown: https://rewindex.com/cve/CVE-2026-59903.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-59903 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:12:31.304Z