CVE-2026-23941

CVE-2026-23941 is a critical-severity vulnerability in Erlang Erlang/inets with a CVSS 3.x base score of 9.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-444.

Key facts

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.

Frequently asked questions

What is CVE-2026-23941?
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.
How severe is CVE-2026-23941?
CVE-2026-23941 has a CVSS 3.x base score of 9.4, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability low.
Is CVE-2026-23941 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-23941?
CVE-2026-23941 primarily affects Erlang Erlang/inets. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-23941?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-23941 have an EU (EUVD) identifier?
Yes. CVE-2026-23941 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-11776.
When was CVE-2026-23941 published?
CVE-2026-23941 was published on 2026-03-13 and last updated on 2026-06-17.

References

Affected products (2)

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