{"affected":[{"ranges":[{"events":[{"introduced":"07b8f441ca711f9812fad9e9115bab3c3aa92f79"},{"fixed":"865d203e4a6a8f44179eced9e1428f9259e4a3bb"}],"repo":"https://github.com/erlang/otp","type":"GIT"}]}],"aliases":["GHSA-h6f3-hx58-xhj6","CVE-2026-42792"],"credits":[{"name":"Ryan Moore","type":"FINDER"},{"name":"John Högberg","type":"REMEDIATION_DEVELOPER"}],"database_specific":{"capec_ids":["CAPEC-227"],"cpe_ids":["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-755","CWE-770"]},"details":"## Summary\n\nImproper Handling of Exceptional Conditions vulnerability in Erlang OTP erts (epmd) allows an unauthenticated remote attacker to permanently terminate the Erlang Port Mapper Daemon (epmd) via connection slot exhaustion.\n\nThe do\\_accept function in erts/epmd/src/epmd\\_srv.c calls epmd\\_cleanup\\_exit() when accept(2) returns EMFILE (per-process file descriptor limit reached) or ENFILE (system-wide file descriptor limit reached), rather than treating these as recoverable conditions. An attacker can exhaust epmd's file descriptor slots by holding many TCP connections open while periodically sending a single byte to reset the idle timeout, then causing accept(2) to return EMFILE, which kills the daemon. epmd has no per-source-IP connection cap, making the attack feasible from a single source.\n\nOn Debian/Ubuntu default packaging the impact is amplified: the systemd unit inherits a low file descriptor soft limit, and repeated daemon deaths trigger systemd's start-rate-limit, permanently failing both epmd.service and epmd.socket and requiring manual operator intervention to recover.\n\nThis issue affects OTP from OTP 17.0 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15.\n\n## Workaround\n\n\\* Restrict epmd to loopback only by adding a systemd socket override: set ListenStream= (empty, to clear), then ListenStream=127.0.0.1:4369 and ListenStream=\\[::1\\]:4369 in /etc/systemd/system/epmd.socket.d/override.conf.\n\\* On systemd-managed systems, raise the file descriptor limit and configure automatic restart by adding LimitNOFILE=65536 and Restart=always with a suitable RestartSec in /etc/systemd/system/epmd.service.d/override.conf.\n\\* Restrict network access to TCP port 4369 via firewall rules to trusted hosts only.","id":"EEF-CVE-2026-42792","modified":"2026-07-27T16:11:33.934Z","published":"2026-07-27T14:58:24.426Z","references":[{"type":"ADVISORY","url":"https://github.com/erlang/otp/security/advisories/GHSA-h6f3-hx58-xhj6"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-42792.html"},{"type":"WEB","url":"https://www.erlang.org/doc/system/versions.html#order-of-versions"},{"type":"FIX","url":"https://github.com/erlang/otp/commit/865d203e4a6a8f44179eced9e1428f9259e4a3bb"}],"related":[],"schema_version":"1.7.3","severity":[{"score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","type":"CVSS_V4"}],"summary":"epmd permanent DoS via EMFILE on accept(2) in erts","upstream":[]}