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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Erlang | OTP | 17.0, 5.10 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | erlang | 1:27.3.4.9+dfsg-1 | — |
| Debian 13 | erlang | 1:27.3.4.1+dfsg-1+deb13u2 | — |
| Debian 12 | erlang | 1:25.2.3+dfsg-1+deb12u4 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | erlang | 1:27.3.4.6+dfsg-1ubuntu0.1 | USN-8827-1 |
| Ubuntu 25.10 | erlang | No fix yet | — |
| Ubuntu 24.04 LTS | erlang | 1:25.3.2.8+dfsg-1ubuntu4.7 | USN-8827-1 |
| Ubuntu 22.04 LTS | erlang | 1:24.2.1+dfsg-1ubuntu0.7 | USN-8827-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | erlang | 1:22.2.7+dfsg-1ubuntu0.5+esm2 | USN-8827-1 |
| Ubuntu Pro 18.04 LTS | erlang | 1:20.2.2+dfsg-1ubuntu2+esm3 | USN-8827-1 |
| Ubuntu Pro 16.04 LTS | erlang | 1:18.3-dfsg-1ubuntu3.1+esm3 | USN-8827-1 |
| Ubuntu Pro 14.04 LTS | erlang | 1:16.b.3-dfsg-1ubuntu2.2+esm2 | USN-8827-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | erlang27 | 27.1.3-2.1 | openSUSE-SU-2026:10947-1 |
| openSUSE Leap 16.0 | erlang | 27.1.3-160000.4.1 | openSUSE-SU-2026:20607-1 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | erlang | 26.2.5.18-1 | — |
Advisories 4
- USN-8827-1 erlang vulnerabilities Ubuntu Security Notices (USN) · Sep 28, 2026
- WID-SEC-2026-0721 Erlang/OTP: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 28, 2026
- openSUSE-SU-2026:10947-1 erlang27-27.1.3-2.1 on GA media SUSE / openSUSE Security Updates · Jun 4, 2026
- openSUSE-SU-2026:20607-1 Security update for erlang SUSE / openSUSE Security Updates · Apr 24, 2026
References
- Request smuggling via first-wins Content-Length parsing in inets httpd vendor-advisory related
- EEF CNA record for CVE-2026-23941 related
- OSV record EEF-CVE-2026-23941 related
- Erlang/OTP version ordering
- Fix commit e775a33 in erlang/otp patch
- Fix commit a761d39 in erlang/otp patch
- Fix commit a4b4633 in erlang/otp patch