GHSA-P6Q4-FGR8-VX4P

StackOverflowException via nested array initializers bypasses ExpressionDepthLimit fix (GHSA-wgh7-7m3c-fx25)

Details

The recent fix for GHSA-wgh7-7m3c-fx25 (uncontrolled recursion in parser) added ExpressionDepthLimit defaulting to 250. However, deeply nested array initializers ([[[[...) recurse through ParseArrayInitializer → ParseExpression → ParseArrayInitializer, which is a different recursion path not covered by the expression depth counter.

This causes a StackOverflowException on current main (commit b5ac4bf - "Add limits for default safety").

PoC

using Scriban;

// ExpressionDepthLimit (default 250) does NOT prevent this crash
string nested = "{{ " + new string('[', 5000) + "1" + new string(']', 5000) + " }}";
Template.Parse(nested); // StackOverflowException - process terminates

Same as GHSA-wgh7-7m3c-fx25: High severity. StackOverflowException cannot be caught with try/catch in .NET - the process terminates immediately. Any application calling Template.Parse with untrusted input is vulnerable, even with the new default ExpressionDepthLimit enabled.

GHSA-P6Q4-FGR8-VX4P has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (7.0.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is GHSA-P6Q4-FGR8-VX4P? GHSA-P6Q4-FGR8-VX4P is a high-severity security vulnerability in Scriban (nuget), affecting versions < 7.0.0. It is fixed in 7.0.0.
2. How severe is GHSA-P6Q4-FGR8-VX4P? GHSA-P6Q4-FGR8-VX4P has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of Scriban are affected by GHSA-P6Q4-FGR8-VX4P? Scriban (nuget) versions < 7.0.0 is affected.
4. Is there a fix for GHSA-P6Q4-FGR8-VX4P? Yes. GHSA-P6Q4-FGR8-VX4P is fixed in 7.0.0. Upgrade to this version or later.
5. Is GHSA-P6Q4-FGR8-VX4P exploitable, and should I be worried? Whether GHSA-P6Q4-FGR8-VX4P is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether GHSA-P6Q4-FGR8-VX4P is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix GHSA-P6Q4-FGR8-VX4P? Upgrade Scriban to 7.0.0 or later.