OTP applications are reusable software components in Erlang/OTP, usually organized as modules and services that provide specific functions. A deployment’s enabled applications and configuration determine which capabilities—and which code paths—are active.
This matters for security because a vulnerability in an OTP component may affect only systems that include or use that component in a vulnerable way. Defenders should inventory Erlang/OTP versions and enabled applications, then compare them with the affected components and versions in an advisory. Disabling an unnecessary application or limiting access to exposed services can reduce risk, but applying the vendor’s fix is the primary remediation when a deployment is affected.