The vulnerability in Scriban arises from the ArrayFunctions.InsertAt method, which fills the array with null entries up to the specified index without enforcing any loop or recursion limits such as LoopLimit or LimitToString. This unbounded allocation loop can be triggered by templates using array.insert_at with a very large index parameter, causing rapid memory exhaustion and an OutOfMemoryException. Unlike other similar functions hardened in version 7.0.0, InsertAt lacks a context-aware overload that would enforce limits, making it possible to bypass existing safety controls. The failure mode is severe because OutOfMemoryException is generally not catchable and leads to host process termination. The vulnerability affects Scriban versions before 7.2.0.

Exploitation causes the host process running the Scriban template renderer to crash due to an OutOfMemoryException triggered by unbounded memory allocation. This results in a denial-of-service condition where the application or service hosting the template engine is terminated unexpectedly. The vulnerability does not require privileges or user interaction and can be triggered by crafted templates specifying large index values in array.insert_at calls.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. The recommended fix pattern is to add a context-aware overload of InsertAt that enforces LoopLimit and other safety controls before performing allocations, and to mark the unsafe overload as ignored for script usage. Until a patch is available, avoid processing untrusted templates that use array.insert_at with large index values to prevent potential denial-of-service. Monitor vendor communications for an official fix release.