CVE-2026-42608

Grav: Unauthenticated Path Traversal & Arbitrary File Write in FormFlash component.

State: Published
Severity: 8.8 High
Published: May 11, 2026
Updated: May 11, 2026
Reserved: Apr 29, 2026

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.

Scores

CVSS	Score	Vector	Source
4.0	8.8 High	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	GitHub_M

Weaknesses

CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Affected Products

Product	Versions
gravgetgrav	< 2.0.0-beta.2Affected

References

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

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