CVE-2026-57852 Grav CMS scheduler-webhook plugin vulnerability
Grav CMS scheduler-webhook plugin contains an authentication bypass vulnerability that allows unauthenticated remote attackers to trigger configured scheduled jobs by exploiting a short-circuit logic flaw in the webhook token validation. Attackers can send a single unauthenticated POST request to the scheduler webhook endpoint to execute all configured scheduled jobs or target a specific job, causing unintended execution of operator-defined commands under the web server process user.
Browse PHP security risksQuick answer
Trilby Media Grav CMS scheduler-webhook plugin should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- <= 1.1.3
- <= 2.0.8
Fixed versions
- Apply the latest vendor-supported patched version.
How to fix it
CVE-2026-57852 affects Grav CMS scheduler-webhook plugin and involves authentication bypass. Successful exploitation may let an attacker bypass an expected login or multi-factor authentication check. Treat this as a high-priority fix, especially when the affected component or endpoint is reachable by untrusted users. Update the Grav scheduler-webhook plugin to the fixed release named by its advisory when available; until then, disable the webhook endpoint or place it behind strong authentication and a network allowlist.
- Inventory every deployment, device, package, plugin, container, build, and environment that uses Grav CMS scheduler-webhook plugin.
- Compare the installed version with the recorded affected range: <= 1.1.3, <= 2.0.8.
- Update the Grav scheduler-webhook plugin to the fixed release named by its advisory when available; until then, disable the webhook endpoint or place it behind strong authentication and a network allowlist.
- Until patched, restrict the affected API or workflow to trusted administrators and enforce an additional access-control layer at the proxy or network boundary.
- Review configuration, roles, tokens, network paths, and exposed endpoints connected to Grav CMS scheduler-webhook plugin; remove access that is not required.
- Review authentication, API, audit, and object-change logs for cross-user access, bypassed checks, or unexpected privileged actions.
- If exploitation is suspected, isolate affected assets, preserve evidence, rotate exposed credentials or keys, restore trusted data, and rebuild compromised systems before returning them to service.
Scan now. Google sign-in is only needed to unlock fix guidance.
Verify the fix
- Confirm every affected asset now runs the fixed vendor-supported release or has the documented mitigation for CVE-2026-57852 in place.
- Use a safe regression test to confirm the affected authentication bypass path no longer produces the vulnerable behavior.
- Confirm temporary access controls, endpoint restrictions, network blocks, and least-privilege settings remain effective after the update.
- Review post-remediation logs and rerun Fixnx plus the relevant package, dependency, firmware, browser, or product-specific security check.
- Document affected assets, versions, changes, validation evidence, reviewed logs, and any credential rotation, cleanup, or replacement completed.
Related categories
Related security risks
More published guidance from the same primary category.
Trusted references
FAQ
What is affected by CVE-2026-57852?
Trilby Media Grav CMS scheduler-webhook plugin versions listed as affected should be reviewed: <= 1.1.3, <= 2.0.8.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.