# CVE-2026-42608 — getgrav grav

> As of 2026-05-11, CVE-2026-42608 is a CRITICAL-severity vulnerability in getgrav grav, CVSS v3.1 9.1, EPSS 0.5% (41.9th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-42608, most recently “ShinyHunters Exploit Grav CMS Path Traversal (CVE-2026-42608) to Hack Clop Ransomware Gang's Leak Site”.

**Last updated:** 2026-05-11

## What is CVE-2026-42608?

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.

The record classifies CVE-2026-42608 under weakness class [CWE-22](https://intel.threadlinqs.com/cwe/CWE-22). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 147 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 9.1 — CRITICAL (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **CVSS v4.0 base score:** 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`)
- **EPSS (FIRST):** 0.5% probability of exploitation in the next 30 days, higher than 41.9% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 8.2/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-05-11

## Is CVE-2026-42608 being exploited?

Weaponised exploit code for CVE-2026-42608 is publicly available. 1 public proof-of-concept repository is tracked for this identifier.

- [trickest/cve](https://github.com/trickest/cve/blob/main/2026/CVE-2026-42608.md) (trickest)

## Affected products and versions

- **getgrav**: grav

Affected software packages:

- `composer:getgrav/grav` — patched in 2.0.0-beta.2

## How to fix CVE-2026-42608

Fixed versions are recorded for 1 package: composer:getgrav/grav 2.0.0-beta.2. Vendor advisory: [https://github.com/getgrav/grav/security/advisories/GHSA-hmcx-ch82-3fv2](https://github.com/getgrav/grav/security/advisories/GHSA-hmcx-ch82-3fv2). Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

## Threat activity tracking CVE-2026-42608

1 tracked threat in the Threadlinqs corpus references CVE-2026-42608, either in the campaign’s CVE list or as an indicator on the campaign record.

- [ShinyHunters Exploit Grav CMS Path Traversal (CVE-2026-42608) to Hack Clop Ransomware Gang's Leak Site](https://intel.threadlinqs.com/threat/TL-2026-2671) — CRITICAL · 2026-09-26

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on 2026-09-27. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [github.com](https://github.com/getgrav/grav/security/advisories/GHSA-hmcx-ch82-3fv2)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-42608
Full detection coverage and IOCs for threats exploiting CVE-2026-42608 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp