CVE-2026-69213: high-severity vulnerability in http4s
Http4s Ember HTTP/2: unbounded outbound frame queue
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, Ember HTTP/2 serializes outbound frames through one unbounded queue consumed by writeLoop. When the peer stops reading, an unauthenticated HTTP/2 client can continue sending PING, SETTINGS, or DATA frames that cause Ember to enqueue acknowledgments or WINDOW_UPDATE frames faster than the writer drains them, exhausting heap memory on a server built with withHttp2. The shared behavior also affects an ember-client connected to a hostile HTTP/2 server, and the patch replaces the unbounded path with bounded, backpressured outbound queues. 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%