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.
https://www.vulncheck.com/advisories/scriban-before-denial-of-service-via-uncontrolled-recursion
https://github.com/scriban/scriban/security/advisories/GHSA-wgh7-7m3c-fx25
Published: 2026-08-16
Updated: 2026-08-16
Base Score: 7.8
Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C
Severity: High
Base Score: 7.5
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Severity: High
Base Score: 8.7
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Severity: High