CVE-2026-69203
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, An Ember server with HTTP/2 enabled through withHttp2 does not enforce SETTINGS_MAX_CONCURRENT_STREAMS for peer-created streams. One unauthenticated connection can open an unbounded number of streams, each retaining per-stream state until heap exhaustion. The same unchecked allocation is reachable in an ember-client through server-initiated PUSH_PROMISE frames because enablePush is not enforced. 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_3 (JAVA):
Affected version(s) >=0.22.0-M8 <0.23.35Fix Suggestion:
Update to version 0.23.35org.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_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-M47Related Resources (5)
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)
EPSS
Base Score:
0.46