Scriban has a Stack Overflow via Nested Array Initializers That Bypass the ExpressionDepthLimit FixGHSA-p6q4-fgr8-vx4p
HIGHGHSA-p6q4-fgr8-vx4p is a high-severity (CVSS 7.5) CWE-674 vulnerability in Scriban. A fix is available for Scriban — see the affected versions and patch details below.
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for GHSA-p6q4-fgr8-vx4p.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
Scriban.NETScriban.SignedReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
Summary
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
Impact
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Scriban | all versions | 7.0.0dotnet add package Scriban --version 7.0.0 |
| .NETNuGet | Scriban.Signed | all versions | 7.0.0dotnet add package Scriban.Signed --version 7.0.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Scriban, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Scriban to 7.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-p6q4-fgr8-vx4p is resolved across your whole dependency graph.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.
Frequently Asked Questions
Is GHSA-p6q4-fgr8-vx4p in your dependencies?
Find it across NuGet, including transitive dependencies.