{"cve":"CVE-2026-88975","nvd":{"published":"2026-09-15T20:19:19.943","modified":"2026-09-16T20:39:16.610","status":"Deferred","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-400"],"references":["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","https://github.com/http4s/http4s/security/advisories/GHSA-gq9p-f254-h286"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:54:41.405518556+00:00"},"epss":{"cve":"CVE-2026-88975","score":0.0063,"percentile":0.5019,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-gq9p-f254-h286","url":"https://osv.dev/vulnerability/GHSA-gq9p-f254-h286","summary":"Http4s: Ember HTTP/2 buffers a frame's declared payload before checking SETTINGS_MAX_FRAME_SIZE","modified":"2026-09-15T20:15:05.144198128Z","packages":[{"ecosystem":"Maven","name":"org.http4s:http4s-ember-core_2.13","purl":"pkg:maven/org.http4s/http4s-ember-core_2.13","ranges":["<0.23.37"],"fixed":["0.23.37"]},{"ecosystem":"Maven","name":"org.http4s:http4s-ember-core_2.12","purl":"pkg:maven/org.http4s/http4s-ember-core_2.12","ranges":["<0.23.37"],"fixed":["0.23.37"]},{"ecosystem":"Maven","name":"org.http4s:http4s-ember-core_3","purl":"pkg:maven/org.http4s/http4s-ember-core_3","ranges":["<0.23.37"],"fixed":["0.23.37"]},{"ecosystem":"Maven","name":"org.http4s:http4s-ember-core_2.13","purl":"pkg:maven/org.http4s/http4s-ember-core_2.13","ranges":[">=1.0.0-M1 <1.0.0-M48"],"fixed":["1.0.0-M48"]},{"ecosystem":"Maven","name":"org.http4s:http4s-ember-core_3","purl":"pkg:maven/org.http4s/http4s-ember-core_3","ranges":[">=1.0.0-M1 <1.0.0-M48"],"fixed":["1.0.0-M48"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}