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Grav Admin Plugin vulnerable to Cross-Site Scripting (XSS) Stored endpoint `/admin/config/site` parameter `data[taxonomies]`

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

Summary

A Stored Cross-Site Scripting (XSS) vulnerability was identified in the /admin/config/site endpoint of the Grav application. This vulnerability allows attackers to inject malicious scripts into the data[taxonomies] parameter. The injected payload is stored on the server and automatically executed in the browser of any user who accesses the affected site configuration, resulting in a persistent attack vector.

Details

Vulnerable Endpoint: POST /admin/config/site
Parameter: data[taxonomies]

The application does not properly validate or sanitize input in the data[taxonomies] field. As a result, an attacker can inject JavaScript code, which is stored in the site configuration and later rendered in the administrative interface or site output, causing automatic execution in the user's browser.

PoC

Payload:

"><script>alert('XSS-PoC')</script>

Steps to Reproduce:

  1. Log in to the Grav Admin Panel with sufficient permissions to modify site configuration.

  2. Navigate to Configuration > Site.

  3. In the Taxonomies Types field (which maps to data[taxonomies]), insert the payload above:

    "><script>alert('XSS-PoC')</script>

  4. Save the configuration.

Pasted image 20250718195942

  1. Go on Pages and click on one of them

Pasted image 20250718200306

  1. The stored payload is executed immediately in the browser, confirming the Stored XSS vulnerability.

Pasted image 20250718200353

  1. The HTTP request submitted during this process contains the vulnerable parameter and payload:

Pasted image 20250718200445

Impact

Stored XSS attacks can lead to severe consequences, including:

  • Session hijacking: Stealing cookies or authentication tokens to impersonate users

  • Credential theft: Harvesting usernames and passwords using malicious scripts

  • Malware delivery: Distributing unwanted or harmful code to victims

  • Privilege escalation: Compromising administrative users through persistent scripts

  • Data manipulation or defacement: Changing or disrupting site content

  • Reputation damage: Eroding trust among site users and administrators

Discoverer

Marcelo Queiroz

by CVE-Hunters

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 v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements Present
Privileges Required High
User interaction Active
Vulnerable System Impact Metrics
Confidentiality High
Integrity None
Availability None
Subsequent System Impact Metrics
Confidentiality High
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:A/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N

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.
(7th percentile)

Weaknesses

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Learn more on MITRE.

CVE ID

CVE-2025-66308

GHSA ID

GHSA-gqxx-248x-g29f

Source code

Credits

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