# CVE-2026-69205: Http4s: Ember Transfer-Encoding value parsing (TE.CL / TE.0 request smuggling) > Attackers can exploit request smuggling in Http4s Ember to bypass access controls, hijack requests, or poison caches due to incorrect header parsing. - **Severity:** High 8.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N`) - **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-9998-894r-fwvr ## What is CVE-2026-69205? CVE-2026-69205 is a high-severity 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 HeaderP.parse uses a case-sensitive substring test for the Transfer-Encoding value and decodes header bytes with the platform default charset. Values such as Chunked are not recognized, values such as notchunked are incorrectly accepted, and Unicode case folding can turn a Kelvin-sign byte sequence into a match when UTF-8 is used. Intermediaries that apply RFC-compliant token and charset rules can therefore disagree with Ember’s Content-Length or zero-length framing, enabling TE.CL or TE.0 request smuggling, access-control bypass, cross-user request hijacking, and cache poisoning on the server path. Response smuggling through an ember-client gateway requires a malicious or compromised upstream. This issue is fixed in versions 0.23.35 and 1.0.0-M47. Weakness: CWE-444 (Inconsistent Interpretation of HTTP Requests) ## Which versions are affected by CVE-2026-69205? 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-2026-69205? 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-2026-69205 being exploited? There is no known exploitation of CVE-2026-69205 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-69205 and fix it if it is affected. What it is: CVE-2026-69205 is a high-severity 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-2026-69205 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-2026-69205/ (Markdown: https://insights.sbomify.com/CVE-2026-69205/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-69205 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-69205 - OSV: https://osv.dev/vulnerability/CVE-2026-69205 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-69205/ Summaries are generated and may contain mistakes; the official description above is the record.