CVE-2026-692049.2CriticalCWE-444

CVE-2026-69204: Http4s: Ember accepts Transfer-Encoding combined with Content-Length (CL.TE request smuggling)

http4s

Affected: http4s · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.6%probability of exploitation in the next 30 days

47th percentile

050100

Higher than 47% of scored CVEs

9.2CriticalCVSS 4.0

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

http4s · http4s< 0.23.35; >= 1.0.0-M1, < 1.0.0-M47

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Inconsistent Interpretation of HTTP Requests · Injection and Smuggling
Vendor: http4s
Published: September 2026
Band: Unlikely (under 1%), September 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-69204 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.