CVE-2026-59903

Netty: Cache Poisoning and Information Disclosure via CORS Vary Header Overwrite

HIGH

7.5

CVSS Score

Published: August 17, 2026 at 05:56 PM UTC

Updated: September 23, 2026 at 03:38 PM UTC

1 product affected across 1 vendorNetty

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Severity

HIGH7.5

Exploit prediction

EPSS 0.3%

SSVC

No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Netty · Nettymaven

95%

v < 4.1.137v < 4.1.137.Finalv < 4.2.17.Final4.2.0 ≤ v < 4.2.17

Affected range stops below 4.1.137, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.1.137.Final, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.2.17, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.2.17.Final, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (5)

x_refsource_CONFIRMVendor Advisory

Source: cverecord

https://github.com/netty/netty/security/advisories/GHSA-8c42-7qj2-3j46

x_refsource_MISCIssue TrackingPatch

Source: cverecord

https://github.com/netty/netty/pull/17213

x_refsource_MISCIssue TrackingPatch

Source: cverecord

https://github.com/netty/netty/pull/17217

x_refsource_MISCRelease Notes

Source: cverecord

https://github.com/netty/netty/releases/tag/netty-4.1.137.Final

x_refsource_MISCRelease Notes

Source: cverecord

https://github.com/netty/netty/releases/tag/netty-4.2.17.Final

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGH[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: HIGH
Integrity: NONE
Availability: NONE

Vector?

Quick Info

StatusANALYZED

CWE

CWE-524

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