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Vulnerability · Published Mar 13, 2026 · Assigned by EEF

CVE-2026-23941Request smuggling via first-wins Content-Length parsing in inets httpd

High 7.0

In plain English

A high-severity security flaw in OTP from Erlang. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)7.0High
Exploit odds (30 days)0.5%top 58.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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 28.4.1, OTP 27.3.4.9 and OTP 26.2.5.18, corresponding to inets from 5.10 before 9.6.1, 9.3.2.3 and 9.1.0.5.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12erlang1:25.2.3+dfsg-1+deb12u4DEBIAN-CVE-2026-23941
Debian:13erlang1:27.3.4.1+dfsg-1+deb13u2DEBIAN-CVE-2026-23941
Debian:14erlang1:27.3.4.9+dfsg-1DEBIAN-CVE-2026-23941
Ubuntu:22.04:LTSerlang1:24.2.1+dfsg-1ubuntu0.7USN-8827-1
Ubuntu:22.04:LTSerlang1:24.2.1+dfsg-1ubuntu0.7UBUNTU-CVE-2026-23941
Ubuntu:24.04:LTSerlang1:25.3.2.8+dfsg-1ubuntu4.7USN-8827-1
Ubuntu:24.04:LTSerlang1:25.3.2.8+dfsg-1ubuntu4.7UBUNTU-CVE-2026-23941
Ubuntu:25.10erlangno fix listedUBUNTU-CVE-2026-23941
Ubuntu:26.04:LTSerlang1:27.3.4.6+dfsg-1ubuntu0.1UBUNTU-CVE-2026-23941
Ubuntu:26.04:LTSerlang1:27.3.4.6+dfsg-1ubuntu0.1USN-8827-1

Affected products (as reported)

VendorProductVersions
Erlang OTP 5.10 – before *
Erlang OTP 17.0 – before *84adefa331c4159d432d22840663c38f155cd4c1 – before *

Weakness: CWE-444 · Vector: 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

References