CVE-2026-69218High· 7.5▾ TwilightHttp4s 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 w…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 41.3 · likelihood 0.1 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake.
Exploit-prediction probability, daily snapshots since Sep 17.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
Last analysed / modified upstream
0.5%
Http4s 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.
Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Affected packages:
org.http4s:http4s-ember-core_2.12 <= 0.23.34org.http4s:http4s-ember-core_2.13 <= 0.23.34org.http4s:http4s-ember-core_3 <= 0.23.34org.http4s:http4s-ember-core_2.13 >= 1.0.0-M1, <= 1.0.0-M46org.http4s:http4s-ember-core_3 >= 1.0.0-M1, <= 1.0.0-M46Patched in:
org.http4s:http4s-ember-core_2.12 0.23.35org.http4s:http4s-ember-core_2.13 0.23.35org.http4s:http4s-ember-core_3 0.23.35org.http4s:http4s-ember-core_2.13 1.0.0-M47org.http4s:http4s-ember-core_3 1.0.0-M47Connected by shared product, vendor, weakness, or advisory.
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