Answer in brief
CVE-2026-100659 records a Medium severity (CVSS 6.9) vulnerability in Netty 4.2.0 through 4.2.17 HTTP/3 Request Routing Bypass. The current sources do not mark it as known exploited. The current feed maps netty/netty (generic). 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 6.9. 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). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| netty/nettygeneric | >=4.2.0.Final <4.2.18.Final | 4.2.18.Final |
Published upstream
Sep 26, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 27, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 26, 2026
Netty's HTTP/3 codec (io.netty:netty-codec-http3) in versions 4.2.0.Final through 4.2.17.Final does not enforce the RFC 9114 requirement that the :authority pseudo-header field and a literal host header field, when both present, carry the same value. A remote unauthenticated peer can send a single HEADERS frame containing both fields with differing, attacker-controlled values; the request is accepted and delivered to the application with two conflicting authorities, allowing routing, virtual-host, and access-control decisions to be bypassed when different components in the request path consult different fields. This issue is fixed in 4.2.18.Final.
Quoted source text, attributed separately from HOL analysis.