Executive brief
Erlang/OTP is a programming platform used to build highly scalable and distributed systems. A flaw in its secure communication module allows unauthorized users to bypass network restrictions intended to limit access to the local network. If an attacker possesses a valid security certificate from the same provider, they can gain full control over the system, potentially leading to data theft or service disruption.
Technical details
A logic error in the inet_tls_dist:check_ip/1 function causes a failure in LAN allowlist enforcement for Erlang distribution over TLS. The function incorrectly calls inet:sockname/1 (local address) instead of inet:peername/1 (remote address) to identify the connecting peer. Consequently, the subnet mask comparison compares the local IP against itself, always succeeding regardless of the actual remote IP. An attacker with a valid CA-signed TLS certificate can bypass the LAN restriction to gain full Erlang distribution access, enabling remote code execution via rpc:call/4. This affects OTP 26.0 through versions prior to 29.0.2, 28.5.0.2, and 27.3.4.13.
Affected products
- Erlang OTP/ssl 26.0 to 27.3.4.12, 28.0 to 28.5.0.1, 29.0 to 29.0.1
Timeline
- 2026-06-10: disclosed
- 2026-06-10: advisory
- 2026-06-10: patched