Request smuggling via first-wins Content-Length parsing in inets httpd
Summary
| CVE | CVE-2026-23941 |
|---|---|
| State | PUBLISHED |
| Assigner | EEF |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-03-13 19:54:15 UTC |
| Updated | 2026-11-11 20:17:07 UTC |
| Description | Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling') vulnerability in Erlang OTP (inets httpd module) allows HTTP Request Smuggling. This vulnerability is associated with program files lib/inets/src/http_server/httpd_request.erl and program routines httpd_request:parse_headers/7. The server does not reject or normalize duplicate Content-Length headers. The earliest Content-Length in the request is used for body parsing while common reverse proxies (nginx, Apache httpd, Envoy) honor the last Content-Length value. This violates RFC 9112 Section 6.3 and allows front-end/back-end desynchronization, leaving attacker-controlled bytes queued as the start of the next request. This issue affects OTP from OTP 17.0 before OTP 26.2.5.18, OTP 27.3.4.9, and OTP 28.4.1, corresponding to inets from 5.10 before 9.1.0.5, 9.3.2.3, and 9.6.1. Whether OTP before OTP 17.0, corresponding to inets before 5.10, is affected is unknown. |
Risk And Classification
Primary CVSS: v4.0 7 HIGH from 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.000230000 probability, percentile 0.061880000 (date 2026-04-07)
Problem Types: CWE-444 | CWE-444 CWE-444 Inconsistent Interpretation of HTTP Requests
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | Secondary | 7 | HIGH | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:L/E:X/C... |
| 4.0 | CNA | CVSS | 7 | HIGH | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:L |
| 3.1 | [email protected] | Primary | 9.4 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L |
CVSS v4.0 Breakdown
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Erlang | Erlang/inets | All | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Erlang | OTP | affected 17.0 * otp | Not specified |
| CNA | Erlang | OTP | affected 5.10 * otp | Not specified |
| CNA | Erlang | OTP | affected 84adefa331c4159d432d22840663c38f155cd4c1 * git | Not specified |
| CNA | Erlang | OTP | unaffected e775a332f623851385ab6ddb866d9b150612ddf6 * git | Not specified |
| CNA | Erlang | OTP | unaffected a761d391d8d08316cbd7d4a86733ba932b73c45b * git | Not specified |
| CNA | Erlang | OTP | unaffected a4b46336fd25aa100ac602eb9a627aaead7eda18 * git | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/erlang/otp/commit/a4b46336fd25aa100ac602eb9a627aaead7eda18 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | Patch |
| cna.erlef.org/cves/CVE-2026-23941.html | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | cna.erlef.org | Vendor Advisory |
| www.erlang.org/doc/system/versions.html | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | www.erlang.org | Product |
| github.com/erlang/otp/security/advisories/GHSA-w4jc-9wpv-pqh7 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | Vendor Advisory |
| github.com/erlang/otp/commit/a761d391d8d08316cbd7d4a86733ba932b73c45b | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | Patch |
| osv.dev/vulnerability/EEF-CVE-2026-23941 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | osv.dev | Third Party Advisory |
| github.com/erlang/otp/commit/e775a332f623851385ab6ddb866d9b150612ddf6 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | Patch |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Luigino Camastra / Aisle Research (en)
CNA: Konrad Pietrzak (en)
Additional Advisory Data
Workarounds
CNA: * Configure frontend proxy to reject requests with duplicate Content-Length headers. * Disable HTTP keep-alive on httpd by adding {keep_alive, false} to httpd configuration. Note: This impacts performance for clients making multiple requests. * Deploy a Web Application Firewall (WAF) configured to reject requests with multiple Content-Length headers.