{"id":"CVE-2026-47244","state":"PUBLISHED","title":"Netty HTTP/2: Advertised MAX_CONCURRENT_STREAMS are not enforced","description":"Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, 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. Versions 4.1.135.Final and 4.2.15.Final patch the issue.","publishedAt":"2026-06-12T14:23:50.316Z","updatedAt":"2026-06-12T14:59:15.823Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","source":"GitHub_M"},"assigner":"GitHub_M","products":["netty netty"],"affected":[{"vendor":"netty","product":"netty","versions":[{"version":">= 4.2.0.Final, < 4.2.15.Final","status":"affected"},{"version":"< 4.1.135.Final","status":"affected"}]}],"references":["https://github.com/netty/netty/security/advisories/GHSA-5x3r-wrvg-rp6q","https://github.com/netty/netty/releases/tag/netty-4.1.135.Final","https://github.com/netty/netty/releases/tag/netty-4.2.15.Final"],"weaknesses":["CWE-400"],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/47xxx/CVE-2026-47244.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-47244","state":"PUBLISHED","datePublished":"2026-06-12T14:23:50.316Z","dateUpdated":"2026-06-12T14:59:15.823Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-05-18T22:54:18.272Z"},"containers":{"cna":{"title":"Netty HTTP/2: Advertised MAX_CONCURRENT_STREAMS are not enforced","descriptions":[{"lang":"en","value":"Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, 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. Versions 4.1.135.Final and 4.2.15.Final patch the issue."}],"affected":[{"vendor":"netty","product":"netty","versions":[{"version":">= 4.2.0.Final, < 4.2.15.Final","status":"affected"},{"version":"< 4.1.135.Final","status":"affected"}]}],"references":[{"url":"https://github.com/netty/netty/security/advisories/GHSA-5x3r-wrvg-rp6q","name":"https://github.com/netty/netty/security/advisories/GHSA-5x3r-wrvg-rp6q","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/netty/netty/releases/tag/netty-4.1.135.Final","name":"https://github.com/netty/netty/releases/tag/netty-4.1.135.Final","tags":["x_refsource_MISC"]},{"url":"https://github.com/netty/netty/releases/tag/netty-4.2.15.Final","name":"https://github.com/netty/netty/releases/tag/netty-4.2.15.Final","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":5.3,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-400","lang":"en","description":"CWE-400: Uncontrolled Resource Consumption","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-06-12T14:23:50.316Z"},"source":{"advisory":"GHSA-5x3r-wrvg-rp6q","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-12T14:59:00.141106Z","id":"CVE-2026-47244","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-06-12T14:59:15.823Z"}}]}}}