{"affected":[{"ranges":[{"events":[{"introduced":"d9674f32811cd5bb02b0d6656053b5ee226bc74c"},{"fixed":"d94a94c96eb4cccbd6f7d7da5975f0c035b69612"},{"fixed":"6746dc4e1df5257ad8ac91cbbd167cb8b0274ce7"},{"fixed":"e0050fc00c500a4fa9ba1f594603c787ff6d20b2"}],"repo":"https://github.com/erlang/otp","type":"GIT"}]}],"aliases":["GHSA-pwvh-c689-f8q5","CVE-2026-70399"],"credits":[{"name":"Lukas Backström / Erlang Solutions","type":"FINDER"},{"name":"Lukas Backström / Erlang Solutions","type":"REMEDIATION_DEVELOPER"},{"name":"Konrad Pietrzak / Ericsson","type":"REMEDIATION_REVIEWER"}],"database_specific":{"capec_ids":["CAPEC-469"],"cpe_ids":["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-770"]},"details":"## Summary\n\nAllocation 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 max\\_clients 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.\n\nThe accept gate in httpd\\_manager:handle\\_new\\_connection/4 reads the option with httpd\\_util:lookup/2, which returns undefined when the key is absent, rather than the three-argument form carrying the 150 default that the neighbouring get\\_ustate/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 max\\_clients explicitly are unaffected, because a configured value is applied as intended.\n\nThis 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.\n\n## Workaround\n\n\\* Set max\\_clients explicitly in the httpd configuration, for example {max\\_clients, 150}. An explicitly configured value is read by the same accept gate and applied as intended, so this restores the documented limit without upgrading.\n\\* Limit concurrent connections in front of httpd, for example with reverse proxy or firewall connection-count and connection-rate rules.\n\\* Restrict access to the server to trusted clients where the deployment allows it.\n\n## Configuration\n\nOnly servers that do not set max\\_clients in the httpd configuration are affected. A server that sets the option to any integer value applies the limit as intended.","id":"EEF-CVE-2026-70399","modified":"2026-09-01T14:33:06.173223Z","published":"2026-09-01T14:33:05.717Z","references":[{"type":"ADVISORY","url":"https://github.com/erlang/otp/security/advisories/GHSA-pwvh-c689-f8q5"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-70399.html"},{"type":"WEB","url":"https://www.erlang.org/doc/system/versions.html#order-of-versions"},{"type":"FIX","url":"https://github.com/erlang/otp/commit/d94a94c96eb4cccbd6f7d7da5975f0c035b69612"},{"type":"FIX","url":"https://github.com/erlang/otp/commit/6746dc4e1df5257ad8ac91cbbd167cb8b0274ce7"},{"type":"FIX","url":"https://github.com/erlang/otp/commit/e0050fc00c500a4fa9ba1f594603c787ff6d20b2"}],"related":[],"schema_version":"1.7.3","severity":[{"score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","type":"CVSS_V4"}],"summary":"httpd does not enforce the documented default max_clients connection limit","upstream":[]}