CVE-2026-69209: high-severity vulnerability in http4s
Http4s: WebSocket decoder accepts unbounded message sizes
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.6%
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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
http4s · http4sRelated CVEs — http4s
In the same product, most dangerous first.
CVE-2020-5280HIGHLocal file inclusion vulnerability in http4sEPSS 7.0%CVE-2021-21294HIGHUnbounded connection acceptance in http4s-blaze-serverEPSS 2.2%CVE-2021-32643MEDIUMStaticFile.fromUrl can leak presence of a directoryEPSS 1.4%CVE-2021-41084HIGHResponse Splitting from unsanitized headers in http4sEPSS 1.2%CVE-2023-22465HIGHHttp4s has fatal error parsing User-Agent and Server headersEPSS 0.9%CVE-2026-69208HIGHHttp4s: DigestAuth nonce map grows unboundedEPSS 0.8%