Arcanicanis

**Name of the Vulnerable Software and Affected Versions** Mastodon versions prior to 3.5.17 Mastodon versions 4.0.x prior to 4.0.13 Mastodon versions 4.1.x prior to 4.1.13 Mastodon versions 4.2.x prior to 4.2.5 **Description** The issue is related to insufficient origin validation in Mastodon, allowing attackers to impersonate and take over any remote account. This can be exploited due to a lack of proper validation, enabling malicious actors to bypass authentication procedures. The estimated number of potentially affected devices worldwide is not specified, but the vulnerability affects nearly 12 million users. There is no information about real-world incidents where this issue was exploited. Technical details about exploitation include the fact that attackers can exploit the vulnerability to impersonate users and take over their accounts, but specific API endpoints, vulnerable parameters, or function names are not mentioned. **Recommendations** For Mastodon versions prior to 3.5.17, update to version 3.5.17 or later. For Mastodon versions 4.0.x prior to 4.0.13, update to version 4.0.13 or later. For Mastodon versions 4.1.x prior to 4.1.13, update to version 4.1.13 or later. For Mastodon versions 4.2.x prior to 4.2.5, update to version 4.2.5 or later. As a temporary workaround, consider restricting access to the LDAP configuration for authentication until a patch is available. Monitor account activity for any suspicious behavior and update the Mastodon app promptly.