GHSA-v8x2-fjv7-8hjh
Grav has Broken Access Control which allows an Editor to modify the page's YAML Frontmatter to alter form processing actions
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
getgrav/gravReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Due to a broken access control vulnerability in the /admin/pages/{page_name} endpoint, an editor ( user with full permissions to pages ) can change the functionality of a form after submission.
Details
Due to improper authorization checks when modifying critical fields on a POST request to /admin/pages/{page_name}, an editor with only permissions to change basic content on the form is now able to change the functioning of the form through modifying the content of the data[_json][header][form] which is the YAML frontmatter which includes the process section which dictates what happens after a user submits the form which include some important actions that could lead to further vulnerabilities.
PoC
-
Have Admin and Form plugins installed
-
Connect to panel as admin, create user and give him permission for pages all
-
Now connect as that user and notice you cant edit any process field in the panel
-
Change anything in the content of the form and save
-
Intercept the request:
-
Now modify the field `data[_json][header][form] with the following payload URL-encoded not like this:
{"name":"ssti-test 2","fields":{"name":{"type":"text","label":"Name","required":true}},"buttons":{"submit":{"type":"submit","value":"Submit"}},"process":[{"message":"{{ evaluate_twig(form.value('name')) }}"}]}
- Change the field and forward it:
Request goes through and changes have been made to the form.
Impact
- Attacker can modify submission logic of the form which leads to changing redirect value, email sending, changing template, breaking out of the Twig sandbox potentially executing code...
Fix recommendation
- Implement proper authorization checks to such requests especially when it contains fields user shouldn't be able to modify based on his role.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | getgrav/grav | all versions | 1.8.0-beta.27 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for getgrav/grav. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update getgrav/grav to 1.8.0-beta.27 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-v8x2-fjv7-8hjh is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-v8x2-fjv7-8hjh is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-v8x2-fjv7-8hjh. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-v8x2-fjv7-8hjh in your dependencies?
O3 detects GHSA-v8x2-fjv7-8hjh across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.