CVE-2026-42608

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.

CVSS v3.1 Score

9.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0012

Probability of exploitation

0.31%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-22 Path Traversal

Affected Products

Vendor	Product	Versions
getgrav	grav	< 2.0.0
getgrav	grav	All

References

Advisories & Patches

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

Exploits

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

Frequently Asked Questions

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. It has a CVSS v3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-42608? +

CVE-2026-42608 has a CVSS v3.1 score of 9.1 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0012, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-42608? +

CVE-2026-42608 affects products from getgrav, specifically: grav. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-42608? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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