Vulnerabilidades de Scriban

Scriban before 6.6.0 contains an uncontrolled recursion vulnerability in its recursive-descent parser. The parser does not enforce a default expression depth limit (the ExpressionDepthLimit property in ParserOptions defaults to null/disabled), so an attacker who controls template input can supply a deeply nested template (e.g., thousands of nested parentheses or blocks) that exhausts thread stack space and raises a StackOverflowException. Because a StackOverflowException cannot be caught in .NET, this causes immediate, unrecoverable termination of the hosting process, resulting in a denial of service. Applications that process untrusted or user-supplied templates can be exploited remotely without authentication.

Scriban before 6.6.0 contains an infinite recursion vulnerability in object rendering when the ObjectRecursionLimit property defaults to unlimited. Attackers can supply circular reference objects to the template context, exhausting stack space and triggering an uncatchable StackOverflowException that terminates the hosting process.

Scriban before 7.0.0 (affected versions <= 6.6.0) contains a stack overflow vulnerability in nested array initializer parsing. Deeply nested array initializers recurse through a path (ParseArrayInitializer → ParseExpression → ParseArrayInitializer) that is not covered by the ExpressionDepthLimit counter added in the fix for GHSA-wgh7-7m3c-fx25. An attacker who can supply untrusted input to Template.Parse can trigger an uncatchable StackOverflowException that immediately terminates the process, even with the default ExpressionDepthLimit enabled.

Scriban before 7.0.0 fails to clear the CachedTemplates dictionary when TemplateContext.Reset() is called, allowing cached templates to persist across reused contexts. Attackers can exploit request-dependent ITemplateLoader implementations to access previously authorized template content from earlier renders without triggering TemplateLoader.Load() again.

Scriban before 7.0.0 (affected <= 6.6.0) applies its LoopLimit constraint only to script loop statements and not to expensive iteration performed inside built-in operators and functions. As a result, a single expression such as {{ 1..1000000 | array.size }} — or a memory-amplification expression such as {{ 'A' * 200000000 }} — can force large CPU or memory consumption even when LoopLimit is configured to a very small value, resulting in denial of service. Applications that render attacker-controlled templates and rely on LoopLimit for safe execution are affected.

Scriban before 7.0.0 (affected versions <= 6.6.0) contains an uncontrolled memory allocation vulnerability in the string.pad_left and string.pad_right template functions, which perform no validation on the width parameter before delegating to .NET's String.PadLeft/PadRight. When an application exposes Scriban to untrusted template input, an attacker can supply an arbitrarily large width value (e.g., 500,000,000) to trigger ~1GB memory allocations in a single call, resulting in OutOfMemoryException and denial of service. The TemplateContext.LimitToString limit does not prevent this because it is only enforced after the string has been fully allocated.

Scriban before 7.0.0 contains an uncontrolled recursion vulnerability in the object.to_json builtin function that lacks depth limits and circular reference detection. Attackers can craft templates with self-referencing objects to trigger unbounded recursion, causing a StackOverflowException that fatally terminates the hosting .NET process.

Scriban before 7.2.0 contains a denial of service vulnerability in the array.insert_at function that allocates unbounded null entries without respecting LoopLimit or LimitToString constraints. Attackers can supply a large index parameter to trigger OutOfMemoryException and crash the host process in under a second.

Scriban versions from 3.0.0 through 7.2.5 contain a denial of service vulnerability in the ScriptRange.Multiply operator that bypasses LoopLimit when the left operand is a lazy sequence. Attackers can supply templates with array multiplication on lazy sequences to execute billions of uncharged iterations, pinning CPU cores and exhausting garbage collection resources even when LoopLimit is set to 1.

Scriban versions 3.0.0 through 7.2.0 contain a denial of service vulnerability in the array multiplication operator that allocates memory without enforcing LoopLimit or overflow-safe arithmetic checks. Attackers can supply a large integer multiplier in a template to force multi-gigabyte memory allocations, causing resource exhaustion and availability degradation.