CVE-2026-69218
Published:September 15, 2026
Updated:September 22, 2026
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.
Affected Packages
https://github.com/http4s/http4s.git (GITHUB):
Affected version(s) >=v0.22.0-M8 <v0.23.35Fix Suggestion:
Update to version v0.23.35https://github.com/http4s/http4s.git (GITHUB):
Affected version(s) >=v1.0.0-M1 <v1.0.0-M47Fix Suggestion:
Update to version v1.0.0-M47org.http4s:http4s-ember-core_2.13 (JAVA):
Affected version(s) >=1.0.0-M2 <1.0.0-M47Fix Suggestion:
Update to version 1.0.0-M47org.http4s:http4s-ember-core_2.13 (JAVA):
Affected version(s) >=0.10.0-M10 <0.23.35Fix Suggestion:
Update to version 0.23.35org.http4s:http4s-ember-core_3 (JAVA):
Affected version(s) >=1.0.0-M22 <1.0.0-M47Fix Suggestion:
Update to version 1.0.0-M47org.http4s:http4s-ember-core_2.12 (JAVA):
Affected version(s) >=0.10.0-M10 <0.23.35Fix Suggestion:
Update to version 0.23.35org.http4s:http4s-ember-core_3 (JAVA):
Affected version(s) >=0.22.0-M8 <0.23.35Fix Suggestion:
Update to version 0.23.35Related Resources (6)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
Allocation of Resources Without Limits or Throttling
EPSS
Base Score:
0.46