Vulnerability · Published May 11, 2026 · Assigned by GitHub_M

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

High 8.8

In plain English

A high-severity path traversal in grav from getgrav. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)8.8High

Exploit odds (30 days)0.6%top 51.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Packagist	getgrav/grav	2.0.0-beta.2	GHSA-hmcx-ch82-3fv2

Affected products (as reported)

Vendor	Product	Versions
getgrav	grav	< 2.0.0-beta.2

Weakness: CWE-22 · Vector: 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

References

https://github.com/getgrav/grav/security/advisories/GHSA-hmcx-ch82-3fv2 x_refsource_CONFIRM