{"id":"CVE-2026-69209","aliases":["EUVD-2026-79173","GHSA-jrxx-w2m8-5hf5"],"status":"published","title":"Http4s: WebSocket decoder accepts unbounded message sizes","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, The shared WebSocket decoder permits unbounded message buffering because defragmentation accumulates fragments without a limit and FrameTranscoder accepts declared lengths up to Int.MaxValue. A remote client that completes a WebSocket handshake against an http4s-blaze-server or http4s-ember-server endpoint can exhaust server memory with oversized frames or fragmented messages. The patched decoder applies a configurable 64 MiB default limit to individual frames and defragmented messages through EmberServerBuilder.withMaxWebSocketMessageSize. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.0063,"percentile":0.50474,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-400","CWE-770"],"published":"2026-09-15T18:55:29Z","modified":"2026-10-28T02:30:56Z","products":[{"vendor":"http4s","product":"http4s"}],"references":[{"url":"https://github.com/http4s/http4s/security/advisories/GHSA-jrxx-w2m8-5hf5","tags":["x_refsource_CONFIRM","advisory"]},{"url":"https://github.com/http4s/http4s/commit/d578c3c9da6193627d40fa785e612cda7fcd77b3","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/http4s/http4s/releases/tag/v0.23.35","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/http4s/http4s/releases/tag/v1.0.0-M47","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/69xxx/CVE-2026-69209.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-69209","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-69209","title":"Http4s: WebSocket decoder accepts unbounded message sizes","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, The shared WebSocket decoder permits unbounded message buffering because defragmentation accumulates fragments without a limit and FrameTranscoder accepts declared lengths up to Int.MaxValue. A remote client that completes a WebSocket handshake against an http4s-blaze-server or http4s-ember-server endpoint can exhaust server memory with oversized frames or fragmented messages. The patched decoder applies a configurable 64 MiB default limit to individual frames and defragmented messages through EmberServerBuilder.withMaxWebSocketMessageSize. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T18:55:29.782Z","modified":"2026-09-16T18:37:15.546Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-400","CWE-770"],"updated_at":"2026-11-02T13:50:16.178634Z"}],"euvd":[{"id":"EUVD-2026-79173","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, The shared WebSocket decoder permits unbounded message buffering because defragmentation accumulates fragments without a limit and FrameTranscoder accepts declared lengths up to Int.MaxValue. A remote client that completes a WebSocket handshake against an http4s-blaze-server or http4s-ember-server endpoint can exhaust server memory with oversized frames or fragmented messages. The patched decoder applies a configurable 64 MiB default limit to individual frames and defragmented messages through EmberServerBuilder.withMaxWebSocketMessageSize. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T18:55:29Z","modified":"2026-09-16T18:37:15Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T17:28:14.33177Z"}],"nvd":[{"id":"CVE-2026-69209","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, The shared WebSocket decoder permits unbounded message buffering because defragmentation accumulates fragments without a limit and FrameTranscoder accepts declared lengths up to Int.MaxValue. A remote client that completes a WebSocket handshake against an http4s-blaze-server or http4s-ember-server endpoint can exhaust server memory with oversized frames or fragmented messages. The patched decoder applies a configurable 64 MiB default limit to individual frames and defragmented messages through EmberServerBuilder.withMaxWebSocketMessageSize. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T19:17:37.87Z","modified":"2026-09-16T20:39:16.61Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-400","CWE-770"],"updated_at":"2026-11-02T14:12:47.668237Z"}],"osv":[{"id":"CVE-2026-69209","title":"Http4s: WebSocket decoder accepts unbounded message sizes","description":"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, The shared WebSocket decoder permits unbounded message buffering because defragmentation accumulates fragments without a limit and FrameTranscoder accepts declared lengths up to Int.MaxValue. A remote client that completes a WebSocket handshake against an http4s-blaze-server or http4s-ember-server endpoint can exhaust server memory with oversized frames or fragmented messages. The patched decoder applies a configurable 64 MiB default limit to individual frames and defragmented messages through EmberServerBuilder.withMaxWebSocketMessageSize. This issue is fixed in versions 0.23.35 and 1.0.0-M47.","status":"published","published":"2026-09-15T18:55:29.782Z","modified":"2026-10-28T02:30:56.854538975Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-400","CWE-770"],"updated_at":"2026-11-02T15:45:15.164658Z"}]}}