Scriban before 7.0.0 (affected versions <= 6.6.0) contains an uncontrolled memory allocation vulnerability in the string.pad_left and string.pad_right template functions, which perform no validation on the width parameter before delegating to .NET's String.PadLeft/PadRight. When an application exposes Scriban to untrusted template input, an attacker can supply an arbitrarily large width value (e.g., 500,000,000) to trigger ~1GB memory allocations in a single call, resulting in OutOfMemoryException and denial of service. The TemplateContext.LimitToString limit does not prevent this because it is only enforced after the string has been fully allocated.
https://www.vulncheck.com/advisories/scriban-before-denial-of-service-via-string-pad-left-pad-right
https://github.com/scriban/scriban/security/advisories/GHSA-v66j-x4hw-fv9g
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