Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V4 - API and Web Service HTTP request consistency
|
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Alert meAnalysisAIv1 – Sep 15, 2026
Request smuggling in http4s Ember affects ember-core (server and client) before 0.23.35 and 1.0.0-M47 because the chunked decoder trims chunk-size tokens and accepts leading '+' or '-' signs instead of requiring hexadecimal digits followed by the mandatory CRLF. When Ember runs behind an intermediary that forwards chunked bodies without re-encoding and parses chunk boundaries differently, an unauthenticated attacker can achieve TE.TE request smuggling that bypasses intermediary controls, poisons shared caches, or hijacks queued requests; the same response-path leniency enables response smuggling when ember-client is used as a gateway in front of a malicious or compromised upstream. No public exploit code or CISA KEV entry is associated with this issue at time of analysis, and no EPSS score was supplied in the source data.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 5 packages in maven, euvd
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Severity by source
AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
Primary rating from Vendor (github) · only source for this CVE.
CVSS VectorVendor: github
Lifecycle Timeline
1DescriptionCVE.org
Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s chunk decoder trims the chunk-size token and accepts leading plus or minus signs instead of requiring one or more hexadecimal digits followed by the required CRLF. When an intermediary forwards chunked data without re-encoding and interprets malformed chunk boundaries differently, an unauthenticated attacker can create TE.TE request smuggling that bypasses intermediary controls, poisons caches, or hijacks the request queue. The same response-path leniency can enable response smuggling against an ember-client used as a gateway when the upstream is malicious or compromised. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
Blast Radius
ecosystem impact- 3 maven packages depend on org.http4s:http4s-ember-core_2.12 (2 direct, 1 indirect)
Ecosystem-wide dependent count for version 0.23.35.
Threat Intelligence Overview
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.
HTTP request smuggling exploits inconsistencies in how front-end and back-end servers parse HTTP message boundaries.
EUVD-2026-79176
GHSA-jrpm-956j-96jg
NVD
CVE.org
EPSS
Exploit-DB