High [CVE-2026-42792] Erlang OTP epmd: Remote Denial of Service via connection exhaustion
This high-severity Red Hat Linux advisory covers CVE-2026-42792 affecting Red Hat Hardened Images.
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Summary
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.
The 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.
On 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.
This issue affects OTP from OTP 17.0 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15. By exhausting connection slots through holding numerous TCP connections open and periodically sending data, the attacker can force epmd to terminate, leading to a permanent Denial of Service (DoS).
- < 17.0
- < 29.0.4
- < 28.5.0.4
- < 27.3.4.15
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
- erlang27-main-27.3.4.15-0.1.hum1
- RHSA-2026:47009
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
Mitigation
Upgrade to a fixed release: erlang27-main-27.3.4.15-0.1.hum1, RHSA-2026:47009. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
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