Description

Scriban before 7.0.0 caches TypedObjectAccessor by Type only without considering MemberFilter changes, allowing reused TemplateContext instances to expose members that should be hidden. Attackers can access filtered properties and fields by reusing a TemplateContext after tightening its MemberFilter, bypassing sandbox policies across requests or tenants.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.1",
  "pubDate": "2026-08-16T14:16:57.050Z",
  "pubdate": "2026-08-16T14:16:57.050Z",
  "executiveSummary": "Scriban before version 7.0.0 suffers from a caching flaw in the TypedObjectAccessor component, leading to a security sandbox bypass vulnerability.\nThe vulnerability allows malicious actors to access filtered properties and fields by reusing a TemplateContext instance after tightening its MemberFilter.\nThe affected product is Scriban in versions prior to 7.0.0.\nThe risk implications include cross-tenant or cross-request data exposure and unauthorized access to restricted object members in multi-tenant or sandboxed template evaluation environments.\nAttacker capabilities involve leveraging shared or reused TemplateContext instances to bypass intended access control policies and security boundaries.\nExploitation requires the reuse of TemplateContext instances across requests or tenants where MemberFilter restrictions are dynamically modified or tightened.",
  "technicalDetails": "The root cause of the vulnerability lies within the caching mechanism of the TypedObjectAccessor component in Scriban.\nTypedObjectAccessor caches object access patterns strictly by Type without taking into consideration subsequent changes or modifications made to the MemberFilter.\nWhen a TemplateContext instance is reused across multiple template evaluations, or across different tenants and requests, previously cached accessors persist despite the application of stricter MemberFilter policies.\nConsequently, members that should be hidden or restricted under a newly tightened MemberFilter remain accessible through the stale cache entries generated during prior evaluations.\nThe attack flow proceeds as follows: an initial template evaluation populates the TypedObjectAccessor cache under a permissive MemberFilter configuration. Subsequently, the application tightens the MemberFilter on the same TemplateContext instance to enforce stricter isolation or privacy controls. An attacker then submits a payload or template that requests previously filtered properties or fields. Because the cache relies solely on the underlying Type rather than the current MemberFilter state, the accessor bypasses the updated filter checks and exposes the restricted members.\nThe vulnerable component is the TypedObjectAccessor within the Scriban templating engine affecting all versions prior to 7.0.0.\nAuthentication and privilege requirements depend on the host application architecture, but exploitation typically occurs within multi-tenant platforms or sandboxed environments where untrusted template authors interact with shared execution contexts.\nNetwork exposure is inherent to any application utilizing Scriban to process untrusted template inputs over network interfaces.\nThe post-exploitation impact includes unauthorized data disclosure, exposure of sensitive internal object fields and properties, and complete compromise of the sandbox isolation boundary between execution contexts or tenants."
}