Vulnerability in Http4s
CVE-2026-69210
Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, WebSocket FrameTranscoder.bodyLength rejects extended payload lengths above Integer.MAX_VALUE but permits negative 64-bit lengths. A remote client that completes a WebSocket handshake through an Ember server can send such a frame, causing the decoder to return an empty frame without advancing its input. The decode loop then runs indefinitely, pins a worker at full CPU, and grows an ArrayBuffer without bound, resulting in denial of service. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Http4s — versions < 0.23.35, >= 1.0.0-M1, < 1.0.0-M47
Weakness classification (CWE)
References
- https://github.com/http4s/http4s/security/advisories/GHSA-3j86-pj9g-jchr (x_refsource_CONFIRM)
- https://github.com/http4s/http4s/commit/c7d3ef90dc2ed1cd464968ab1b34f2f1762ddae2 (x_refsource_MISC)
- https://github.com/http4s/http4s/releases/tag/v0.23.35 (x_refsource_MISC)
- https://github.com/http4s/http4s/releases/tag/v1.0.0-M47 (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-69210?
- CVE-2026-69210 is a high-severity vulnerability in Http4s, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 7.5/10. Published 2026-09-15.
- How severe is CVE-2026-69210?
- High severity. CVSS v3 base score is 7.5 out of 10.