CVE-2026-69210Http4s: WebSocket decoder accepts negative length, causing infinite decode loop
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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
- 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-835, CWE-1284
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Deferred
- Record last updated
- Sep 17, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
http4s http4s http4s:http4s (from the name) | before 0.23.35; from 1.0.0-M1, < 1.0.0-M47 | CNA record |
References
- https://github.com/http4s/http4s/security/advisories/GHSA-3j86-pj9g-jchrx-refsource-confirm
- https://github.com/http4s/http4s/commit/c7d3ef90dc2ed1cd464968ab1b34f2f1762ddae2x-refsource-misc
- https://github.com/http4s/http4s/releases/tag/v0.23.35x-refsource-misc
- https://github.com/http4s/http4s/releases/tag/v1.0.0-M47x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.