Horizon Alert
Summary of the vulnerability and why it matters
This advisory details a vulnerability in the Scriban template engine that could allow unauthorized modification of data within applications. The weakness lies in how Scriban handles object property access, potentially enabling malicious code to alter properties, even those intended to be private, leading to the permanent modification of live data after template rendering. The main concern at this time is confirming relevance and exposure to our systems.
- Template engine can alter sensitive data.
- Impacts applications using Scriban templates.
- Assess Scriban usage and potential exposure.
Attack Path
How an attacker could exploit the issue
An attacker could exploit this vulnerability by submitting specially crafted template code to an application that uses a vulnerable version of Scriban. This code, when processed by the TypedObjectAccessor feature, bypasses standard security checks. If successful, the attacker could alter critical properties of live host objects, leading to permanent and potentially severe changes within the application's environment.
- Requires access to a system using vulnerable Scriban.
- Triggered by submitting malicious template code.
- Risk of altering live host object properties.
Live Threat
Current exploitation, exposure, and threat context
When Scriban is used in applications that render user-supplied templates, an access-modifier bypass vulnerability could allow template code to write to CLR object properties that lack setter-visibility checks. This could lead to the permanent alteration of live host objects after template rendering by modifying properties with private, internal, or init-only setters, or through mass assignment on public-setter properties.
- Application objects could be altered.
- Malicious templates could exploit setters.
- Compromised application state may occur.
Operational Fix
Recommended remediation, mitigation, and detection steps
This vulnerability in Scriban impacts applications that use it for template rendering, potentially allowing unauthorized modification of live host objects. Application owners and platform teams are likely responsible for managing this dependency. The first practical step is to identify all instances of Scriban within your environment, confirm their reachability and business criticality, and then coordinate with the accountable owners to plan remediation.
- Application owners should own remediation.
- Verify Scriban usage and template input sources.
- Plan for library updates during maintenance windows.
