Platform
php
Component
flarum/core
Fixed in
1.0.1
1.0.2
CVE-2021-32671 describes a critical Cross-Site Scripting (XSS) vulnerability in Flarum Core, a popular open-source forum software. This flaw allows attackers to inject malicious HTML markup into user input fields, which is then executed in the browsers of other forum users. The vulnerability affects versions of Flarum Core up to and including v1.0.1, and a fix is available in version 1.0.2.
The impact of this XSS vulnerability is significant. An attacker could inject arbitrary JavaScript code into a victim's browser, potentially stealing cookies, session tokens, or redirecting users to malicious websites. This could lead to account takeover, data theft, and further compromise of the forum and its users. The vulnerability was initially discovered in the forum search box, demonstrating the ease with which attackers could exploit it. The ability to execute arbitrary code within the context of the forum's domain grants the attacker a high degree of control over the user's browsing experience.
CVE-2021-32671 was publicly disclosed on June 7, 2021. While no active exploitation campaigns have been definitively linked to this specific vulnerability, the ease of exploitation and the potential impact make it a high-priority target. No public proof-of-concept exploits were immediately released, but the vulnerability's nature makes it likely that such exploits exist or could be easily created. The vulnerability is not currently listed on the CISA KEV catalog.
Exploit Status
EPSS
0.76% (73% percentile)
CVSS Vector
The primary mitigation for CVE-2021-32671 is to immediately upgrade Flarum Core to version 1.0.2 or later. Before upgrading, it is highly recommended to create a full backup of your Flarum installation, including the database and files. If the upgrade process causes issues, consider rolling back to a previous version using the backup. While upgrading, review any custom extensions for potential vulnerabilities that could be exploited in conjunction with this XSS flaw. After upgrading, confirm the fix by attempting to inject a simple HTML payload (e.g., <script>alert('test')</script>) into a user input field and verifying that the script does not execute.
Actualice Flarum Core a la versión 1.0.2 o superior. Esta versión corrige una vulnerabilidad XSS que permite la ejecución de código malicioso en el navegador del usuario. La actualización se puede realizar a través del panel de administración de Flarum o mediante Composer.
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CVE-2021-32671 is a critical Cross-Site Scripting (XSS) vulnerability in Flarum Core versions up to 1.0.1, allowing attackers to inject malicious HTML and execute scripts in users' browsers.
If you are running Flarum Core version 1.0.1 or earlier, you are affected by this vulnerability. Upgrade to version 1.0.2 or later immediately.
Upgrade Flarum Core to version 1.0.2 or later. Back up your installation before upgrading and test the upgrade thoroughly.
While no confirmed active exploitation campaigns are publicly known, the vulnerability's ease of exploitation makes it a potential target. Vigilance and prompt patching are crucial.
Refer to the official Flarum security advisory: https://flarum.org/blog/security-update-1.0.2
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