httpd function checkheader/3 rejects duplicate Content-Length (per CVE-2026-23941) but never checks for the TE+CL co-presence that RFC 9112 §6.3 identifies as a probable smuggling attempt. handlebody/3 frames by chunked and silently discards Content-Length. A CL-preferring front-end paired with chunked-preferring inets creates a classic CL.TE front-end/back-end desync.
This issue affects OTP from OTP 17.0 before OTP 27.3.4.17, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 5.10 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2. Whether OTP before OTP 17.0, corresponding to inets before 5.10, is affected is unknown.
Gracefulness code ignored cases that should be rejected, resulting in possible HTTP Request Smuggling opportunities.
This issue affects OTP from OTP 22.2 before OTP 27.3.4.17, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 7.1.2 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2.
httpc memory exhaustion via unbounded response header accumulation
httpd applies no timeout while receiving a request body, parking a worker on a stalled client
Allocation of Resources Without Limits or Throttling vulnerability in Erlang/OTP inets httpd allows an unauthenticated remote attacker to cause denial of service by opening and holding open a large number of connections. The maxclients option is documented to default to 150, and the inets hardening guide presents that limit as the first layer of denial-of-service defence, but a server that does not set it explicitly accepts an unlimited number of simultaneous connections. Establishing the connections is sufficient; no valid request and no authentication are required.
The accept gate in httpdmanager:handlenewconnection/4 reads the option with httpdutil:lookup/2, which returns undefined when the key is absent, rather than the three-argument form carrying the 150 default that the neighbouring getustate/2 uses. Erlang term ordering places every integer before every atom, so the Count =< Max guard holds for any connection count and the server never returns {reject, busy}. Each accepted connection occupies a worker process and a socket for as long as it is held, driving the node towards process, memory and file descriptor exhaustion. Servers that set maxclients explicitly are unaffected, because a configured value is applied as intended.
This issue affects OTP from OTP 17.0 before OTP 27.3.4.17, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 5.10 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2.
Incorrect Authorization vulnerability in Erlang OTP (inets modules) allows unauthenticated access to CGI scripts protected by directory rules when served via scriptalias.
When scriptalias maps a URL prefix to a directory outside DocumentRoot, modauth evaluates directory-based access controls against the DocumentRoot-relative path while modcgi executes the script at the ScriptAlias-resolved path. This path mismatch allows unauthenticated access to CGI scripts that directory rules were meant to protect.
This vulnerability is associated with program files lib/inets/src/httpserver/modalias.erl, lib/inets/src/httpserver/modauth.erl, and lib/inets/src/httpserver/modcgi.erl.
This issue affects OTP from OTP 17.0 until OTP 28.4.2, 27.3.4.10 and 26.2.5.19 corresponding to inets from 5.10 until 9.6.2, 9.3.2.4 and 9.1.0.6.