# CVE-2026-69202: Http4s Ember HTTP/2: unbounded inbound body buffering > A hostile peer can cause memory exhaustion in Http4s Ember HTTP/2 servers or clients by sending data faster than the application consumes it. - **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 15 Sep 2026 - **Updated:** 15 Sep 2026 - **Also known as:** GHSA-6m4x-pp6q-5jmm ## What is CVE-2026-69202? CVE-2026-69202 is a high-severity denial of service vulnerability in http4s, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. ### 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. Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling), CWE-400 (Uncontrolled Resource Consumption) ## Which versions are affected by CVE-2026-69202? 10 open source packages ship an affected version, including org.http4s:http4s-ember-core_2.13, org.http4s:http4s-ember-core_2.12 and org.http4s:http4s-ember-core_3. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `org.http4s:http4s-ember-core_2.13` | Maven | All versions | 0.23.35 | | `org.http4s:http4s-ember-core_2.13` | Maven | All versions | 0.23.35 | | `org.http4s:http4s-ember-core_2.13` | Maven | From 1.0.0-M1 | 1.0.0-M47 | | `org.http4s:http4s-ember-core_2.13` | Maven | From 1.0.0-M1 | 1.0.0-M47 | | `org.http4s:http4s-ember-core_2.12` | Maven | All versions | 0.23.35 | | `org.http4s:http4s-ember-core_2.12` | Maven | All versions | 0.23.35 | | `org.http4s:http4s-ember-core_3` | Maven | All versions | 0.23.35 | | `org.http4s:http4s-ember-core_3` | Maven | All versions | 0.23.35 | | `org.http4s:http4s-ember-core_3` | Maven | From 1.0.0-M1 | 1.0.0-M47 | | `org.http4s:http4s-ember-core_3` | Maven | From 1.0.0-M1 | 1.0.0-M47 | ## How do I fix CVE-2026-69202? Upgrade org.http4s:http4s-ember-core_2.13 to a fixed version for your release line: 0.23.35 or 1.0.0-M47. ## Is CVE-2026-69202 being exploited? There is no known exploitation of CVE-2026-69202 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-69202 and fix it if it is affected. What it is: CVE-2026-69202 is a high-severity denial of service vulnerability in http4s, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-69202 in the wild and no public exploit code. Affected packages and fixed versions: - org.http4s:http4s-ember-core_2.13 (Maven): affected all versions; fixed in 0.23.35 - org.http4s:http4s-ember-core_2.13 (Maven): affected all versions; fixed in 0.23.35 - org.http4s:http4s-ember-core_2.13 (Maven): affected from 1.0.0-M1; fixed in 1.0.0-M47 - org.http4s:http4s-ember-core_2.13 (Maven): affected from 1.0.0-M1; fixed in 1.0.0-M47 - org.http4s:http4s-ember-core_2.12 (Maven): affected all versions; fixed in 0.23.35 - org.http4s:http4s-ember-core_2.12 (Maven): affected all versions; fixed in 0.23.35 - org.http4s:http4s-ember-core_3 (Maven): affected all versions; fixed in 0.23.35 - org.http4s:http4s-ember-core_3 (Maven): affected all versions; fixed in 0.23.35 - org.http4s:http4s-ember-core_3 (Maven): affected from 1.0.0-M1; fixed in 1.0.0-M47 - org.http4s:http4s-ember-core_3 (Maven): affected from 1.0.0-M1; fixed in 1.0.0-M47 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-69202/ (Markdown: https://insights.sbomify.com/CVE-2026-69202/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-69202 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-69202 - OSV: https://osv.dev/vulnerability/CVE-2026-69202 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-69202/ Summaries are generated and may contain mistakes; the official description above is the record.