vulnerability / NVI-00003652 / Revision 3
Grav has Unauthenticated Path Traversal & Arbitrary File Write in its FormFlash component
GitHub lists this reviewed advisory for getgrav/grav. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
9.1 CRITICAL (3.1)
nvd@nist.gov severity; no combined Null risk score.
8.8 HIGH (4.0)
security-advisories@github.com severity; no combined Null risk score.
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
getgrav/grav
source listed< 2.0.0-beta.2
# Vulnerability Report: Grav CMS Unauthenticated Path Traversal & Arbitrary File Write **[ZERO-DAY] Unauthenticated Path Traversal leading to Arbitrary Directory Creation and Configuration Injection** ## Summary Grav CMS (v1.7.49.5 and latest development source) is vulnerable to a Zero-Day Path Traversal vulnerability within the FormFlash core component. By manipulating the session_id (passed as `__form-flash-id` in POST requests), an unauthenticated attacker can traverse the filesystem to create arbitrary directories and write an `index.yaml` file containing attacker-controlled data. This vulnerability can lead to unauthorized modification of application behavior, potential data integrity issues, and service disruption in production environments. ## Affected Component - Versions: Confirmed in Grav v1.7.49.5 (latest stable) and the latest development source (March 2026). - Class: `Grav\Framework\Form\FormFlash` - Method: `__construct()` / `getTmpDir()` - Parameter: `session_id` (Mapped to `__form-flash-id` in POST requests) ## Vulnerability Details The FormFlash class is used to persist form data across redirects. It constructs a temporary storage path using the provided se
getgrav/grav
source listedECOSYSTEM: introduced 0; fixed 2.0.0-beta.2
# Vulnerability Report: Grav CMS Unauthenticated Path Traversal & Arbitrary File Write **[ZERO-DAY] Unauthenticated Path Traversal leading to Arbitrary Directory Creation and Configuration Injection** ## Summary Grav CMS (v1.7.49.5 and latest development source) is vulnerable to a Zero-Day Path Traversal vulnerability within the FormFlash core component. By manipulating the session_id (passed as `__form-flash-id` in POST requests), an unauthenticated attacker can traverse the filesystem to create arbitrary directories and write an `index.yaml` file containing attacker-controlled data. This vulnerability can lead to unauthorized modification of application behavior, potential data integrity issues, and service disruption in production environments. ## Affected Component - Versions: Confirmed in Grav v1.7.49.5 (latest stable) and the latest development source (March 2026). - Class: `Grav\Framework\Form\FormFlash` - Method: `__construct()` / `getTmpDir()` - Parameter: `session_id` (Mapped to `__form-flash-id` in POST requests) ## Vulnerability Details The FormFlash class is used to persist form data across redirects. It constructs a temporary storage path using the provided se
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. NIST National Vulnerability Database
- vendor patch
The original advisory lists fixed boundaries 2.0.0-beta.2 for getgrav/grav. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
- NVD lastModified does not establish freshness of every associated CPE record.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-hmcx-ch82-3fv2 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- GHSA-hmcx-ch82-3fv2 ↗
GitHub Advisory Database via OSV · vendor advisory
Observed . GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.
- CVE-2026-42608 ↗
NIST National Vulnerability Database · official catalog
Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 3 ·
Source facts changed; compare the preserved prior revision.
- Revision 2 ·
Source facts changed; compare the preserved prior revision.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.