{"id":"CVE-2026-88975","state":"PUBLISHED","title":"Http4s: Ember HTTP/2 buffers a frame's declared payload before checking SETTINGS_MAX_FRAME_SIZE","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.37 and 1.0.0-M48, Ember’s HTTP/2 read loop parses a frame’s 24-bit declared length but waits to buffer the entire payload before comparing it with SETTINGS_MAX_FRAME_SIZE. An unauthenticated peer can declare a payload near 16 MiB on a connection where Ember advertised 16 KiB and either complete or slowly stream it, causing up to 1024-fold memory amplification per connection before processFrame can reject the frame. The shared H2Connection.readLoop affects withHttp2 servers and clients, while HTTP/2-disabled configurations are unaffected, and the patch rejects oversized frames before buffering their payloads. This issue is fixed in versions 0.23.37 and 1.0.0-M48.","publishedAt":"2026-09-15T19:31:25.221Z","updatedAt":"2026-09-16T14:43:14.199Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["http4s http4s"],"affected":[{"vendor":"http4s","product":"http4s","versions":[{"version":"< 0.23.37","status":"affected"},{"version":">= 1.0.0-M1, < 1.0.0-M48","status":"affected"}]}],"references":["https://github.com/http4s/http4s/security/advisories/GHSA-gq9p-f254-h286","https://github.com/http4s/http4s/commit/87cf334fa3f608ef7d3eb359e71e037ba3336d29","https://github.com/http4s/http4s/releases/tag/v0.23.37","https://github.com/http4s/http4s/releases/tag/v1.0.0-M48"],"weaknesses":["CWE-400"],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/88xxx/CVE-2026-88975.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-88975","state":"PUBLISHED","datePublished":"2026-09-15T19:31:25.221Z","dateUpdated":"2026-09-16T14:43:14.199Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-09-10T16:02:31.341Z"},"containers":{"cna":{"title":"Http4s: Ember HTTP/2 buffers a frame's declared payload before checking SETTINGS_MAX_FRAME_SIZE","descriptions":[{"lang":"en","value":"Http4s is a Scala interface for HTTP services. Prior to 0.23.37 and 1.0.0-M48, Ember’s HTTP/2 read loop parses a frame’s 24-bit declared length but waits to buffer the entire payload before comparing it with SETTINGS_MAX_FRAME_SIZE. An unauthenticated peer can declare a payload near 16 MiB on a connection where Ember advertised 16 KiB and either complete or slowly stream it, causing up to 1024-fold memory amplification per connection before processFrame can reject the frame. The shared H2Connection.readLoop affects withHttp2 servers and clients, while HTTP/2-disabled configurations are unaffected, and the patch rejects oversized frames before buffering their payloads. This issue is fixed in versions 0.23.37 and 1.0.0-M48."}],"affected":[{"vendor":"http4s","product":"http4s","versions":[{"version":"< 0.23.37","status":"affected"},{"version":">= 1.0.0-M1, < 1.0.0-M48","status":"affected"}]}],"references":[{"url":"https://github.com/http4s/http4s/security/advisories/GHSA-gq9p-f254-h286","name":"https://github.com/http4s/http4s/security/advisories/GHSA-gq9p-f254-h286","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/http4s/http4s/commit/87cf334fa3f608ef7d3eb359e71e037ba3336d29","name":"https://github.com/http4s/http4s/commit/87cf334fa3f608ef7d3eb359e71e037ba3336d29","tags":["x_refsource_MISC"]},{"url":"https://github.com/http4s/http4s/releases/tag/v0.23.37","name":"https://github.com/http4s/http4s/releases/tag/v0.23.37","tags":["x_refsource_MISC"]},{"url":"https://github.com/http4s/http4s/releases/tag/v1.0.0-M48","name":"https://github.com/http4s/http4s/releases/tag/v1.0.0-M48","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","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:H","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":"2026-09-15T19:31:25.221Z"},"source":{"advisory":"GHSA-gq9p-f254-h286","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-16T14:43:06.919100Z","id":"CVE-2026-88975","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":"2026-09-16T14:43:14.199Z"}}]}}}