Answer in brief
CVE-2026-47244 records a Medium severity (CVSS 5.3) vulnerability in Netty HTTP/2: Advertised MAX_CONCURRENT_STREAMS are not enforced. The current sources do not mark it as known exploited. The current feed maps io.netty:netty-codec-http2 (maven), io.netty:netty-codec-http2 (maven), io.netty:netty-codec-http2 (maven), io.netty:netty-codec-http2 (maven). 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 5.3. 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 io.netty:netty-codec-http2 (maven), io.netty:netty-codec-http2 (maven), io.netty:netty-codec-http2 (maven), io.netty:netty-codec-http2 (maven). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| io.netty:netty-codec-http2maven | >=4.2.0.Final,<=4.2.14.Final | 4.2.15.Final |
| io.netty:netty-codec-http2maven | <=4.1.134.Final | 4.1.135.Final |
| io.netty:netty-codec-http2maven | >=4.2.0.Final <4.2.15.Final | 4.2.15.Final |
| io.netty:netty-codec-http2maven | >=0 <4.1.135.Final | 4.1.135.Final |
Published upstream
Jun 8, 2026
Evidence: source:osv:source_dates:source-dates:recordSource modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:recordFirst seen by HOL
Jun 11, 2026
### Impact DefaultHttp2Connection.DefaultEndpoint initialises maxActiveStreams/maxStreams to Integer.MAX_VALUE, and Http2Settings never inserts SETTINGS_MAX_CONCURRENT_STREAMS by default (Http2Settings.java:305-307 only clamps a user-supplied value). Unless the application explicitly calls initialSettings().maxConcurrentStreams(n), a Netty HTTP/2 server advertises no limit and enforces none locally. Each open stream allocates a DefaultStream object, PropertyMap slots, flow-controller state and IntObjectHashMap entry; with ~2^30 permissible odd stream IDs a single TCP connection can create hundreds of thousands of long-lived stream objects. This is also the precondition for CVE-2023-44487-style Rapid-Reset amplification, where the absence of a low concurrent cap multiplies backend work. ### Resources https://www.rfc-editor.org/rfc/rfc7540.html#section-6.5.2
Quoted source text, attributed separately from HOL analysis.