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Grav is vulnerable to a DOS on the admin panel

Moderate severity GitHub Reviewed Published Dec 1, 2025 in getgrav/grav • Updated Dec 2, 2025

Package

composer getgrav/grav (Composer)

Affected versions

< 1.8.0-beta.27

Patched versions

1.8.0-beta.27

Description

DOS on the admin panel

Severity Rating: Medium

Vector: Denial Of Service

CVE: XXX

CWE: 400 - Uncontrolled Resource Consumption

CVSS Score: 4.9

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

Analysis

A Denial of Service (DoS) vulnerability has been identified in the application related to the handling of scheduled_at parameters. Specifically, the application fails to properly sanitize input for cron expressions. By manipulating the scheduled_at parameter with a malicious input, such as a single quote, the application admin panel becomes non-functional, causing significant disruptions to administrative operations.

The only way to recover from this issue is to manually access the host server and modify the backup.yaml file to correct the corrupted cron expression

Proof of Concept

  1. Change the value of scheduled_at parameter to ' as shown in the following figures at the http://127.0.0.1/admin/tools endpoint, and observe the response in the second figure:
    gravdos2
    Figure: Http request on tool endpoint
    gravdos3
    Figure: Http response on tool endpoint

  2. When trying to access the admin panel, the panel is broken as shown in the following figure. Additionally, the value change is reflected in the backup.yaml file, as shown in the second figure:
    gravdos4
    Figure: Error message view
    gravdos5
    Figure: Backup.yaml file

Workarounds

No workaround is currently known

Timeline

2024-07-24 Issue identified

2024-09-27 Vendor contacted

About X41 D-Sec GmbH

X41 is an expert provider for application security services.
Having extensive industry experience and expertise in the area of information
security, a strong core security team of world class security experts enables
X41 to perform premium security services.

Fields of expertise in the area of application security are security centered
code reviews, binary reverse engineering and vulnerability discovery.
Custom research and IT security consulting and support services are core
competencies of X41.

References

@rhukster rhukster published to getgrav/grav Dec 1, 2025
Published by the National Vulnerability Database Dec 1, 2025
Published to the GitHub Advisory Database Dec 2, 2025
Reviewed Dec 2, 2025
Last updated Dec 2, 2025

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
High
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(10th percentile)

Weaknesses

Uncontrolled Resource Consumption

The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Learn more on MITRE.

CVE ID

CVE-2025-66303

GHSA ID

GHSA-x62q-p736-3997

Source code

Credits

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