Answer in brief
CVE-2026-59903 records a Medium severity (CVSS 6.5) vulnerability in Netty: Cache Poisoning and Information Disclosure via CORS Vary Header Overwrite. The current sources do not mark it as known exploited. The current feed maps netty/netty (generic), io.netty:netty-codec-http (maven), io.netty:netty-codec-http (maven), io.netty:netty-codec-http (maven) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
Answer in brief
CVE-2026-59903 records a Medium severity (CVSS 6.5) vulnerability in Netty: Cache Poisoning and Information Disclosure via CORS Vary Header Overwrite. The current sources do not mark it as known exploited. The current feed maps netty/netty (generic), io.netty:netty-codec-http (maven), io.netty:netty-codec-http (maven), io.netty:netty-codec-http (maven) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps netty/netty (generic), io.netty:netty-codec-http (maven), io.netty:netty-codec-http (maven), io.netty:netty-codec-http (maven) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| netty/nettygeneric | < 4.1.137.Final || >= 4.2.0.Final, < 4.2.17.Final | Not reported |
| io.netty:netty-codec-httpmaven | >=4.2.0.Final <4.2.17.Final | 4.2.17.Final |
| io.netty:netty-codec-httpmaven | >=0 <4.1.137.Final | 4.1.137.Final |
| io.netty:netty-codec-httpmaven | >=4.2.0.Final,<=4.2.16.Final | 4.2.17.Final |
| io.netty:netty-codec-httpmaven | <=4.1.136.Final | 4.1.137.Final |
Published upstream
Aug 17, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 17, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 17, 2026
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.
Quoted source text, attributed separately from HOL analysis.
CVSS is 6.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps netty/netty (generic), io.netty:netty-codec-http (maven), io.netty:netty-codec-http (maven), io.netty:netty-codec-http (maven) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| netty/nettygeneric | < 4.1.137.Final || >= 4.2.0.Final, < 4.2.17.Final | Not reported |
| io.netty:netty-codec-httpmaven | >=4.2.0.Final <4.2.17.Final | 4.2.17.Final |
| io.netty:netty-codec-httpmaven | >=0 <4.1.137.Final | 4.1.137.Final |
| io.netty:netty-codec-httpmaven | >=4.2.0.Final,<=4.2.16.Final | 4.2.17.Final |
| io.netty:netty-codec-httpmaven | <=4.1.136.Final | 4.1.137.Final |
Published upstream
Aug 17, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 17, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 17, 2026
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.
Quoted source text, attributed separately from HOL analysis.