CVE-2026-42792 epmd permanent DoS via EMFILE on accept(2) in erts
An unauthenticated remote attacker can permanently crash the Erlang Port Mapper Daemon by exhausting file descriptors, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42792?
CVE-2026-42792 is a medium-severity denial of service vulnerability in Erlang OTP, published on 27 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
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.
Which versions are affected by CVE-2026-42792?
It affects 2 products.
Products include Erlang Erlang\/Otp, Erlang Erts.
How do I fix CVE-2026-42792?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-42792 being exploited?
There is no known exploitation of CVE-2026-42792 in the wild and no public exploit code.
Other vulnerabilities in Erlang OTP
- CVE-2022-37026 Auth bypass in n/a
- CVE-2016-10253 Memory corruption in n/a
- CVE-2026-55953 TLS 1.2 and DTLS client accepts unoffered anonymous cipher suite, bypassing server authentication
- CVE-2026-49759 Stack buffer overflow in SCTP error cause parsing in inet_drv allows remote VM crash
- CVE-2026-58227 TLS/DTLS denial of service via unbounded recursion on cross-signed peer certificate chain
Sources
Also known as AZL-94199, DEBIAN-CVE-2026-42792, EEF-CVE-2026-42792, GHSA-h6f3-hx58-xhj6, UBUNTU-CVE-2026-42792.