Description

grav-plugin-api versions before 1.0.15 fail to validate Twig content in the translate() endpoint, allowing attackers with api.pages.write permission to persist pages with process.twig enabled. Attackers can submit crafted header and content parameters to execute server-side template injection payloads that are evaluated at render time.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.1",
  "pubDate": "2026-08-18T12:19:32.827Z",
  "pubdate": "2026-08-18T12:19:32.827Z",
  "executiveSummary": "A server-side template injection vulnerability exists in the grav-plugin-api plugin for Grav CMS, specifically impacting versions prior to 1.0.15.\nThe vulnerability resides within the translate() endpoint, which fails to properly validate and sanitize Twig content supplied during page creation and modification requests.\nAttackers capable of authenticating and acquiring the api.pages.write permission can exploit this flaw to persist malicious pages configured with process.twig enabled.\nBy submitting specially crafted header and content parameters, an authenticated adversary can execute arbitrary code via server-side template injection payloads that are dynamically evaluated at render time.\nThe potential impact includes complete compromise of the underlying server execution context, unauthorized data access, and potential lateral movement depending on the privileges of the web application process.\nSuccessful exploitation requires valid authentication credentials, possession of the specific api.pages.write permission, and the ability to interact with the vulnerable translate() endpoint.",
  "technicalDetails": "The vulnerability is rooted in insufficient input validation and improper handling of Twig templating directives within the translate() endpoint of the grav-plugin-api component.\nThe affected component fails to restrict or inspect user-supplied content passed to the page creation and persistence routines, allowing untrusted input to define processing directives such as process.twig.\nThe attack flow begins when an authenticated adversary with the api.pages.write permission crafts a malicious HTTP request directed at the vulnerable endpoint.\nThe attacker supplies specially manipulated header and content parameters designed to inject arbitrary Twig syntax into the page structure being saved to the filesystem or database.\nBecause the application does not sanitize the input or enforce strict type and content checks, the malicious page is successfully persisted with Twig processing enabled.\nSubsequently, when the affected page is accessed and rendered by the Grav CMS rendering engine, the embedded Twig template injection payloads are evaluated.\nThis execution phase triggers the evaluation of arbitrary expressions or code embedded within the template context, running in the context of the web server process.\nThe vulnerable software consists of grav-plugin-api versions prior to 1.0.15.\nPrerequisites for this attack include network access to the API endpoint, valid authentication credentials, and the explicit privilege level of api.pages.write."
}