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

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.

Published: 2026-03-13 Last update: 2026-05-21 Assigner: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db Source: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-23941 is rated Moderate Risk (42.6/100): CVSS High severity, with low exploitation likelihood (EPSS 0.53%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-23941

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.02% 0.53% +0.51%
2 2026-03-13 — 0.02% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-23941

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.0 4.0 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/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 Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:H)
Exploitation depends on constrained or hard-to-reproduce conditions.
Attack requirements (AT:P)
Additional preconditions must be present for exploitation.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:N)
No confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:N)
No integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:N)
No availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:H)
High confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:H)
High integrity impact on subsequent systems.
Subsequent system availability impact (SA:L)
Limited availability impact on subsequent systems.
Exploit maturity (threat) (E:X)
Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:X)
Not evaluated.
Recovery (supplemental) (R:X)
Not evaluated.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:X)
Not evaluated.
Provider urgency (supplemental) (U:X)
Not evaluated.
 — — 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
9.4 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 5.5 [email protected]

Weakness enumeration for CVE-2026-23941

OS Trackers for CVE-2026-23941

vendor priority summary link
debian not yet assigned CVE-2026-23941 not yet assigned priority: Debian including 1 source packages (erlang), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2026-23941
suse medium — https://www.suse.com/security/cve/CVE-2026-23941/
ubuntu medium CVE-2026-23941 medium priority: Ubuntu including 1 source packages (erlang), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): needs-triage 8. https://ubuntu.com/security/CVE-2026-23941

Affected software / configurations for CVE-2026-23941

Vendor Product Version Raw CPE
erlang erlang\/inets >= 5.10, < 9.1.0.5 cpe:2.3:a:erlang:erlang\/inets:*:*:*:*:*:*:*:*
erlang erlang\/inets >= 9.3, < 9.3.2.3 cpe:2.3:a:erlang:erlang\/inets:*:*:*:*:*:*:*:*
erlang erlang\/inets >= 9.6, < 9.6.1 cpe:2.3:a:erlang:erlang\/inets:*:*:*:*:*:*:*:*
erlang erlang\/otp >= 17.0, < 26.2.5.18 cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
erlang erlang\/otp >= 27.0, < 27.3.4.9 cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
erlang erlang\/otp >= 28.0, < 28.4.1 cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*

References for CVE-2026-23941

cvelogic Threat Intelligence