{"id":"CVE-2026-42792","state":"PUBLISHED","title":"epmd permanent DoS via EMFILE on accept(2) in erts","description":"Improper 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.","publishedAt":"2026-07-27T14:58:24.426Z","updatedAt":"2026-07-28T09:55:23.932Z","severity":{"score":6.3,"label":"Medium","version":"4.0","vector":"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","source":"EEF"},"assigner":"EEF","products":["Erlang OTP"],"affected":[{"vendor":"Erlang","product":"OTP","packageName":"erts","packageURL":"pkg:otp/erts?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%20https:%2F%2Fgithub.com%2Ferlang%2Fotp.git","defaultStatus":"unaffected","versions":[{"version":"6.0","status":"affected","lessThan":"*","changes":[{"at":"17.0.4","status":"unaffected"},{"at":"16.4.0.4","status":"unaffected"},{"at":"15.2.7.11","status":"unaffected"}],"versionType":"otp"}],"cpes":["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"],"modules":["epmd_srv"],"programFiles":["epmd/src/epmd_srv.c"],"programRoutines":[{"name":"do_accept"}],"repo":"https://github.com/erlang/otp"},{"vendor":"Erlang","product":"OTP","packageName":"erlang/otp","packageURL":"pkg:github/erlang/otp","defaultStatus":"unaffected","versions":[{"version":"17.0","status":"affected","lessThan":"*","changes":[{"at":"29.0.4","status":"unaffected"},{"at":"28.5.0.4","status":"unaffected"},{"at":"27.3.4.15","status":"unaffected"}],"versionType":"otp"},{"version":"07b8f441ca711f9812fad9e9115bab3c3aa92f79","status":"affected","lessThan":"865d203e4a6a8f44179eced9e1428f9259e4a3bb","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"],"modules":["epmd_srv"],"programFiles":["erts/epmd/src/epmd_srv.c"],"programRoutines":[{"name":"do_accept"}],"repo":"https://github.com/erlang/otp"}],"references":["https://github.com/erlang/otp/security/advisories/GHSA-h6f3-hx58-xhj6","https://cna.erlef.org/cves/CVE-2026-42792.html","https://osv.dev/vulnerability/EEF-CVE-2026-42792","https://www.erlang.org/doc/system/versions.html#order-of-versions","https://github.com/erlang/otp/commit/865d203e4a6a8f44179eced9e1428f9259e4a3bb"],"weaknesses":["CWE-755","CWE-770"],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/42xxx/CVE-2026-42792.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-42792","state":"PUBLISHED","datePublished":"2026-07-27T14:58:24.426Z","dateUpdated":"2026-07-28T09:55:23.932Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-04-29T18:06:33.251Z"},"containers":{"cna":{"title":"epmd permanent DoS via EMFILE on accept(2) in erts","descriptions":[{"lang":"en","value":"Improper 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."}],"affected":[{"vendor":"Erlang","product":"OTP","packageName":"erts","packageURL":"pkg:otp/erts?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%20https:%2F%2Fgithub.com%2Ferlang%2Fotp.git","defaultStatus":"unaffected","versions":[{"version":"6.0","status":"affected","lessThan":"*","changes":[{"at":"17.0.4","status":"unaffected"},{"at":"16.4.0.4","status":"unaffected"},{"at":"15.2.7.11","status":"unaffected"}],"versionType":"otp"}],"cpes":["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"],"modules":["epmd_srv"],"programFiles":["epmd/src/epmd_srv.c"],"programRoutines":[{"name":"do_accept"}],"repo":"https://github.com/erlang/otp"},{"vendor":"Erlang","product":"OTP","packageName":"erlang/otp","packageURL":"pkg:github/erlang/otp","defaultStatus":"unaffected","versions":[{"version":"17.0","status":"affected","lessThan":"*","changes":[{"at":"29.0.4","status":"unaffected"},{"at":"28.5.0.4","status":"unaffected"},{"at":"27.3.4.15","status":"unaffected"}],"versionType":"otp"},{"version":"07b8f441ca711f9812fad9e9115bab3c3aa92f79","status":"affected","lessThan":"865d203e4a6a8f44179eced9e1428f9259e4a3bb","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"],"modules":["epmd_srv"],"programFiles":["erts/epmd/src/epmd_srv.c"],"programRoutines":[{"name":"do_accept"}],"repo":"https://github.com/erlang/otp"}],"references":[{"url":"https://github.com/erlang/otp/security/advisories/GHSA-h6f3-hx58-xhj6","tags":["vendor-advisory","related"]},{"url":"https://cna.erlef.org/cves/CVE-2026-42792.html","tags":["related"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-42792","tags":["related"]},{"url":"https://www.erlang.org/doc/system/versions.html#order-of-versions","tags":["x_version-scheme"]},{"url":"https://github.com/erlang/otp/commit/865d203e4a6a8f44179eced9e1428f9259e4a3bb","tags":["patch"]}],"metrics":[{"cvssV4_0":{"attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":6.3,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"LOW","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-755","description":"CWE-755 Improper Handling of Exceptional Conditions","lang":"en","type":"CWE"},{"cweId":"CWE-770","description":"CWE-770 Allocation of Resources Without Limits or Throttling","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"EEF","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateUpdated":"2026-07-28T09:55:23.932Z"},"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*","versionEndExcluding":"27.3.4.15","vulnerable":true},{"criteria":"cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*","versionEndExcluding":"28.5.0.4","versionStartIncluding":"28.0","vulnerable":true},{"criteria":"cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*","versionEndExcluding":"29.0.4","versionStartIncluding":"29.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"finder","value":"Ryan Moore"},{"lang":"en","type":"remediation developer","value":"John Högberg"}],"impacts":[{"capecId":"CAPEC-227","descriptions":[{"lang":"en","value":"CAPEC-227 Sustained Client Engagement"}]}],"source":{"discovery":"EXTERNAL"},"workarounds":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<ul><li>Restrict epmd to loopback only by adding a systemd socket override: set <tt>ListenStream=</tt> (empty, to clear), then <tt>ListenStream=127.0.0.1:4369</tt> and <tt>ListenStream=[::1]:4369</tt> in <tt>/etc/systemd/system/epmd.socket.d/override.conf</tt>.</li><li>On systemd-managed systems, raise the file descriptor limit and configure automatic restart by adding <tt>LimitNOFILE=65536</tt> and <tt>Restart=always</tt> with a suitable <tt>RestartSec</tt> in <tt>/etc/systemd/system/epmd.service.d/override.conf</tt>.</li><li>Restrict network access to TCP port 4369 via firewall rules to trusted hosts only.</li></ul>"}],"value":"* 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."}],"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-27T17:25:58.879765Z","id":"CVE-2026-42792","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-27T17:26:08.579Z"}}]}}}