23 Oct 2026 15:48:27 UTC
Http4s Ember HTTP/2: unbounded continuation frame accumulation
cve-program · CVE-2026-69218 · Published
CVE-2026-69218
Http4s Ember HTTP/2: unbounded continuation frame accumulation
CVSS 3.1 7.5 HIGHCheck source for fixed versionsKEV status unknown
cve-program · CVE-2026-69218
PublishedHttp4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, When Ember receives an HTTP/2 HEADERS or PUSH_PROMISE frame without END_HEADERS, H2Connection buffers the header block and subsequent CONTINUATION fragments without a size bound. A remote peer can keep an incomplete block open and exhaust heap memory before request decoding, affecting an ember-server or ember-client configured with withHttp2. The remediation tracks accumulated size against SETTINGS_MAX_HEADER_LIST_SIZE derived from EmberServerBuilder.maxHeaderSize or EmberClientBuilder.maxResponseHeaderSize, sends GOAWAY when the limit is exceeded, and applies receiveHeadersTimeout to incomplete blocks. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
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