Netty prior 4.1.137.Final/4.2.17.Final CorsHandler io.netty.handler.codec.http.cors.CorsHandler setVaryHeader information disclosure

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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5.8$0-$5k0.21+

Summaryinfo

A vulnerability labeled as problematic has been found in Netty. Affected by this vulnerability is the function setVaryHeader of the file io.netty.handler.codec.http.cors.CorsHandler of the component CorsHandler. The manipulation results in information disclosure. This vulnerability is known as CVE-2026-59903. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability was found in Netty. It has been classified as problematic. Affected is the function setVaryHeader of the file io.netty.handler.codec.http.cors.CorsHandler of the component CorsHandler. The manipulation with an unknown input leads to a information disclosure vulnerability. CWE is classifying the issue as CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. This is going to have an impact on confidentiality. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-59903 since 07/07/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1592.

Upgrading to version 4.1.137.Final or 4.2.17.Final eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.9
VulDB Meta Temp Score: 5.8

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 6.5
CNA Vector (GitHub_M): 🔒

CVSSv2info

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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Information disclosure
CWE: CWE-200 / CWE-284 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Netty 4.1.137.Final/4.2.17.Final

Timelineinfo

07/07/2026 CVE reserved
08/17/2026 +41 days Advisory disclosed
08/17/2026 +0 days VulDB entry created
08/17/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-59903 (🔒)
GCVE (CVE): GCVE-0-2026-59903
GCVE (VulDB): GCVE-100-391380

Entryinfo

Created: 08/17/2026 20:23
Changes: 08/17/2026 20:23 (64)
Complete: 🔍
Cache ID: 216::103

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