Vulnerability 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.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/http4s/http4s/commit/d578c3c9da6193627d40fa785e612cda7fcd77b3
- https://github.com/http4s/http4s/releases/tag/v0.23.35
- https://github.com/http4s/http4s/releases/tag/v1.0.0-M47
- https://github.com/http4s/http4s/security/advisories/GHSA-jrxx-w2m8-5hf5
FAQ
What is CVE-2026-69209?
CVE-2026-69209 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 ...
How severe is CVE-2026-69209?
CVE-2026-69209 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-69209?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.