Log in Start free

Vulnerability · Published Sep 15, 2026 · Assigned by GitHub_M

CVE-2026-69202Http4s Ember HTTP/2: unbounded inbound body buffering

High 7.5

In plain English

A high-severity uncontrolled resource consumption in http4s from http4s. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.6%top 49.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/2 flow-control window is replenished according to bytes received from the network rather than bytes consumed by the application, while each stream stores DATA in an unbounded channel. A hostile peer can therefore send a body faster than a slow or non-draining application consumes it, retaining payloads in heap on an ember-server or ember-client configured with withHttp2. The patch bounds the per-stream H2Connection body channel so application consumption applies backpressure. This issue is fixed in versions 0.23.35 and 1.0.0-M47.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Mavenorg.http4s:http4s-ember-core_2.120.23.35GHSA-6m4x-pp6q-5jmm
Mavenorg.http4s:http4s-ember-core_2.130.23.35GHSA-6m4x-pp6q-5jmm
Mavenorg.http4s:http4s-ember-core_2.131.0.0-M47GHSA-6m4x-pp6q-5jmm
Mavenorg.http4s:http4s-ember-core_30.23.35GHSA-6m4x-pp6q-5jmm
Mavenorg.http4s:http4s-ember-core_31.0.0-M47GHSA-6m4x-pp6q-5jmm

Affected products (as reported)

VendorProductVersions
http4s http4s < 0.23.35>= 1.0.0-M1, < 1.0.0-M47

Weakness: CWE-400, CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References