Executive brief
Scriban is a templating engine used to dynamically generate text and configuration files. A flaw in how it parses deeply nested array structures allows an attacker to crash any application using it, even when parsing untrusted templates. The crash is instantaneous and unstoppable, resulting in immediate service outage with no opportunity for error recovery.
Technical details
A stack overflow vulnerability exists in Scriban's template parser when handling deeply nested array initializers (e.g., [[[[...]])). The recursion path ParseArrayInitializer → ParseExpression → ParseArrayInitializer is not bounded by the ExpressionDepthLimit counter that was added in a previous fix. An attacker supplying malicious template input to Template.Parse() can trigger an uncatchable StackOverflowException that terminates the process immediately, even when the default 250-level ExpressionDepthLimit is enabled. No authentication or user interaction is required; the vulnerability is reachable over the network if the application accepts external template input. The fix is available in Scriban 7.0.0 and later.
Affected products
- Scriban Scriban <= 6.6.0
Timeline
- 2026-03-22: disclosed: GitHub Security Advisory GHSA-p6q4-fgr8-vx4p published
- 2026: patched: Fix released in Scriban 7.0.0
- 2026-08-16: advisory: CVE-2026-74792 published