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CVE-2026-23941

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

Published: Mar 13, 2026Updated: May 21, 2026 Sources: CVE List NVD BDUCWE-444
NVD MITRE
9.4CVSSCRITICAL
EPSS Score
0.5%
Top 59.6%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:HI:HA:L
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:LAvailability
Low
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Weaknesses

CWE-444

Affected Products

erlang\/inetserlang
Library
OSS Libraries / generic-library
erlang\/otperlang
Library
OSS Libraries / generic-library
OTPErlang
LibraryLibrary
OSS Libraries / generic-library
Debian GNU/LinuxСообщество свободного программного обеспечения
On-premOS
Operating Systems / linux-distro
РЕД ОСООО «Ред Софт»
On-premOS
Operating Systems / linux-distro
erlangoss-projectOSS Librariesaka erlang/otp, otp, erlang/ssh
сообщество свободного программного обеспеченияoss-projectOperating Systemsaka сообщество свободного программного обеспечения, fsf
ооо «ред софт»commercialRUOperating Systemsaka red soft
and 1 more affected products View all →

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available
Workaround Available

MITRE ATT&CK

1 technique
Collection
View detailed technique mapping

References

https://cna.erlef.org/cves/CVE-2026-23941.html
cna.erlef.org
https://github.com/erlang/otp/commit/a4b46336fd25aa100ac602eb9a627aaead7eda18
github.com
https://github.com/erlang/otp/commit/a761d391d8d08316cbd7d4a86733ba932b73c45b
github.com
and 14 more references View all →

Timeline

Published
Mar 13, 2026
Last Updated
May 21, 2026

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