CVE-2025-24018: YesWiki Vulnerable to Authenticated Stored XSS

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-01-21 · updated 2026-06-17
Weakness: CWE-79

Description

YesWiki is a wiki system written in PHP. In versions up to and including 4.4.5, it is possible for an authenticated user with rights to edit/create a page or comment to trigger a stored XSS which will be reflected on any page where the resource is loaded. The vulnerability makes use of the content edition feature and more specifically of the `{{attach}}` component allowing users to attach files/medias to a page. When a file is attached using the `{{attach}}` component, if the resource contained in the `file` attribute doesn't exist, then the server will generate a file upload button containing the filename. This vulnerability allows any malicious authenticated user that has the right to create a comment or edit a page to be able to steal accounts and therefore modify pages, comments, permissions, extract user data (emails), thus impacting the integrity, availability and confidentiality of a YesWiki instance. Version 4.5.0 contains a patch for the issue.

Affected products

yeswiki: before 4.5.0 — fixed in 4.5.0

How to fix

Upgrade to a fixed version: yeswiki 4.5.0. Check the vendor advisory for mitigations.

References

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