CVE-2026-88975
highHttp4s is a Scala interface for HTTP services.
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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Affected products
Not reported by the source (unknown — not "none").
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
No vendor advisory or patch reference tagged by NVD. Check the references below.
References
- https://github.com/http4s/http4s/commit/87cf334fa3f608ef7d3eb359e71e037ba3336d29 security-advisories@github.com
- https://github.com/http4s/http4s/releases/tag/v0.23.37 security-advisories@github.com
- https://github.com/http4s/http4s/releases/tag/v1.0.0-M48 security-advisories@github.com
- https://github.com/http4s/http4s/security/advisories/GHSA-gq9p-f254-h286 security-advisories@github.com