# CVE-2026-42608: Grav: Unauthenticated Path Traversal & Arbitrary File Write in FormFlash component.

> Unauthenticated attackers can exploit path traversal in Grav's FormFlash component to write arbitrary files, potentially disrupting service or modifying application behavior.

- **Severity:** High 8.8 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 May 2026
- **Updated:** 11 May 2026
- **Also known as:** GHSA-hmcx-ch82-3fv2

## What is CVE-2026-42608?

CVE-2026-42608 is a high-severity path traversal vulnerability in Getgrav Grav, published on 11 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Grav is a file-based Web platform. Prior to 2.0.0-beta.2, there is a 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. This vulnerability is fixed in 2.0.0-beta.2.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-42608?

2 open source packages ship an affected version, including getgrav/grav. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `getgrav/grav` | Packagist | All versions | 2.0.0-beta.2 |
| `getgrav/grav` | Packagist | All versions | 2.0.0-beta.2 |

Products: Getgrav Grav.

## How do I fix CVE-2026-42608?

Upgrade getgrav/grav to 2.0.0-beta.2 or later.

## Is CVE-2026-42608 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42608 exists.

## Other vulnerabilities in Getgrav Grav

- [CVE-2023-34251](https://insights.sbomify.com/CVE-2023-34251/): Grav Server Side Template Injection vulnerability (critical 10.0)
- [CVE-2025-46199](https://insights.sbomify.com/CVE-2025-46199/): Cross-site scripting in n/a (critical 9.8)
- [CVE-2021-47812](https://insights.sbomify.com/CVE-2021-47812/): GravCMS 1.10.7 - Arbitrary YAML Write/Update (Unauthenticated) (2) (critical 9.3)
- [CVE-2025-66844](https://insights.sbomify.com/CVE-2025-66844/): Grav may be vulnerable to SSRF attack via Twig Templates (critical 9.1)
- [CVE-2022-2073](https://insights.sbomify.com/CVE-2022-2073/): Code Injection in getgrav/grav (critical 9.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-42608 and fix it if it is affected.

What it is: CVE-2026-42608 is a high-severity path traversal vulnerability in Getgrav Grav, published on 11 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42608 exists.

Affected packages and fixed versions:
- getgrav/grav (Packagist): affected all versions; fixed in 2.0.0-beta.2
- getgrav/grav (Packagist): affected all versions; fixed in 2.0.0-beta.2

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-42608/ (Markdown: https://insights.sbomify.com/CVE-2026-42608/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42608
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42608
- OSV: https://osv.dev/vulnerability/CVE-2026-42608

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42608/
Summaries are generated and may contain mistakes; the official description above is the record.