Answer in brief
CVE-2026-69204 records a Critical severity (CVSS 0.0) vulnerability in Http4s: Ember accepts Transfer-Encoding combined with Content-Length (CL.TE request smuggling). The current sources do not mark it as known exploited. The current feed maps http4s/http4s (generic), org.http4s:http4s-ember-core_2.12 (maven), org.http4s:http4s-ember-core_2.13 (maven), org.http4s:http4s-ember-core_2.13 (maven) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 0.0. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps http4s/http4s (generic), org.http4s:http4s-ember-core_2.12 (maven), org.http4s:http4s-ember-core_2.13 (maven), org.http4s:http4s-ember-core_2.13 (maven) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| http4s/http4sgeneric | < 0.23.35 || >= 1.0.0-M1, < 1.0.0-M47 | Not reported |
| org.http4s:http4s-ember-core_2.12maven | <=0.23.34 | 0.23.35 |
| org.http4s:http4s-ember-core_2.13maven | <=0.23.34 | 0.23.35 |
| org.http4s:http4s-ember-core_2.13maven | >=1.0.0-M1,<=1.0.0-M46 | 1.0.0-M47 |
| org.http4s:http4s-ember-core_3maven | <=0.23.34 | 0.23.35 |
| org.http4s:http4s-ember-core_3maven | >=1.0.0-M1,<=1.0.0-M46 | 1.0.0-M47 |
Published upstream
Sep 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 15, 2026
Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember HTTP/1.1 does not reject messages containing both Transfer-Encoding and Content-Length, so an intermediary and Ember can select different body framing rules. When ember-server is behind a keep-alive intermediary that forwards both headers and frames by Content-Length, an unauthenticated attacker can smuggle a second request, bypass intermediary access controls, poison caches, or cause a victim request to be joined to an attacker-controlled prefix. The shared response parser can also desynchronize an ember-client connection when a malicious or compromised upstream sends both headers. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
Quoted source text, attributed separately from HOL analysis.