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

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 (v1.7.4…

7.5CVSS Score

HIGHSeverity

NOCISA KEV

VulnerabilityImpact Type

📋 Vulnerability Details

CVE ID	CVE-2026-42608
Vendor	composer
Affected Product	getgrav/grav
Vulnerability Type	Vulnerability
CVSS Score	7.5 (HIGH)
Actively Exploited	❌ No known exploitation
Patch Status	See Vendor Advisory →
Reported By	CYBERDUDEBIVASH SENTINEL APEX Intelligence (via github_advisories)

🔬 Technical Analysis

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: Confirme

📚 Advisory References

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