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Sign-up restriction bypass in Mastodon (self-hosted ActivityPub social server) before v4.5.9, v4.4.16, and v4.3.22 allows remote attackers to register accounts on instances that restrict registration by e-mail domain. Because Mastodon validates addresses but does not restrict characters that downstream mail servers interpret differently, a crafted address can pass the allow/deny-list check while ultimately delivering mail to a domain the operator intended to block. No public exploit identified at time of analysis, and EPSS is very low (0.04%), but SSVC rates the flaw automatable with partial technical impact.
Mastodon versions 4.5.x before 4.5.8 and 4.4.x before 4.4.15 allow unauthenticated attackers with prior knowledge of a quote to prevent its correct processing on a target server, resulting in limited integrity and availability impact. The vulnerability exploits timing and knowledge of ActivityPub quote structures to disrupt social content distribution. Patches are available in Mastodon 4.5.8 and 4.4.15; versions 4.3 and earlier are unaffected due to lack of quote support.
Mastodon prior to versions 4.5.8, 4.4.15, and 4.3.21 contains an unauthenticated Open Redirect vulnerability in the `/web/*` route that allows remote attackers to redirect users to arbitrary external domains via specially URL-encoded path segments. An attacker can exploit this to conduct phishing attacks or steal OAuth credentials by crafting malicious links that bypass Rails path normalization through URL-encoded slashes (%2F). No public exploit code or active exploitation has been confirmed at time of analysis.
Mastodon servers with the experimental FASP feature enabled are vulnerable to Server-Side Request Forgery (SSRF) attacks, allowing unauthenticated attackers to register accounts with arbitrary base URLs that force the server to make requests to internal or local addresses. While attackers cannot control the full request path or view responses, this exposure of internal systems to external manipulation could facilitate reconnaissance or attacks on backend infrastructure. Affected versions are 4.4.0-4.4.13 and 4.5.0-4.5.6; a patch is available.
Unauthenticated attackers can bypass FASP administrator approval in Mastodon 4.4.0-4.4.13 and 4.5.0-4.5.6 to subscribe to account events and request content backfill, affecting only servers with the experimental FASP feature enabled. While individual requests cause minor information disclosure of publicly available URIs, repeated exploitation enables denial-of-service attacks. A patch is available to address this authorization bypass.
Mastodon versions prior to 4.3.19, 4.4.13, and 4.5.6 are vulnerable to web cache poisoning in ActivityPub endpoints when AUTHORIZED_FETCH is enabled, allowing cached responses to be served across different user contexts regardless of request signing. An attacker could exploit this to view content intended for non-blocked accounts or cause blocked users to receive empty responses meant for them, potentially bypassing access controls. No patch is currently available for affected deployments.
Mastodon is a free, open-source social network server based on ActivityPub. [CVSS 6.5 MEDIUM]
Mastodon prior to versions 4.5.5, 4.4.12, and 4.3.18 lacks input validation on list and filter names, allowing authenticated users to create arbitrarily long strings that consume excessive server resources and storage. A local attacker can exploit this to degrade system performance or render their own web interface unusable, though no patch is currently available for affected versions.
Mastodon is a free, open-source social network server based on ActivityPub. [CVSS 7.5 HIGH]
Suspended remote users in Mastodon can bypass suspension restrictions and have their posts appear in timelines through boosting and post processing logic errors. This affects all Mastodon versions for older posts, with additional bypass capabilities in versions 4.5.0-4.5.4, 4.4.5-4.4.11, 4.3.13-4.3.17, and 4.2.26-4.2.29, allowing suspended users to inject new content into the system. No patch is currently available for this integrity issue.
Mastodon versions prior to 4.3.17, 4.4.11, and 4.5.4 fail to validate ownership when retrieving severed relationship lists, allowing any authenticated user to enumerate all lost followers and followed accounts across all severance events. This information disclosure vulnerability affects multi-user Mastodon instances where relationship changes due to moderation actions are visible to unauthorized users. An attacker with a local account can systematically access relationship data they should not have permission to view.
Mastodon's IP address filtering bypass (CWE-918) permits attackers to craft requests using unblocked IP ranges to reach local and loopback services, potentially exposing private resources and internal APIs. An unauthenticated remote attacker can exploit incomplete private address range validation in Mastodon instances to perform Server-Side Request Forgery (SSRF) attacks. Patched versions 4.5.4, 4.4.11, 4.3.17, and 4.2.29 are available.
Mastodon is a free, open-source social network server based on ActivityPub Mastodon which facilitates LDAP configuration for authentication. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Allocation of Resources Without Limits vulnerability could allow attackers to exhaust system resources through uncontrolled allocation.
Mastodon is a self-hosted, federated microblogging platform. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Exposure of Sensitive Information vulnerability could allow attackers to access sensitive data that should not be disclosed.
Mastodon is a self-hosted, federated microblogging platform. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Allocation of Resources Without Limits vulnerability could allow attackers to exhaust system resources through uncontrolled allocation.
In Mastodon 4.1.6, API endpoint rate limiting can be bypassed by setting a crafted HTTP request header. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable. No vendor patch available.
Mastodon is a self-hosted, federated microblogging platform. Rated high severity (CVSS 8.2), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Missing Authorization vulnerability could allow attackers to access resources or perform actions without proper authorization checks.
Mastodon is a free, open-source social network server based on ActivityPub. Rated high severity (CVSS 7.7), this vulnerability is remotely exploitable, low attack complexity. This Unrestricted File Upload vulnerability could allow attackers to upload malicious files that can be executed on the server.
Mastodon is a free, open-source social network server based on ActivityPub. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity.
Mastodon is a free, open-source social network server based on ActivityPub. Rated high severity (CVSS 7.4), this vulnerability is remotely exploitable, no authentication required. Public exploit code available.
Mastodon is a free, open-source social network server based on ActivityPub Mastodon allows configuration of LDAP for authentication. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Mastodon is a free, open-source social network server based on ActivityPub. Rated medium severity (CVSS 5.4), this vulnerability is remotely exploitable, low attack complexity. This Cross-Site Scripting (XSS) vulnerability could allow attackers to inject malicious scripts into web pages viewed by other users.
Mastodon is a free, open-source social network server based on ActivityPub. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Mastodon is a free, open-source social network server based on ActivityPub. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Mastodon is a free, open-source social network server based on ActivityPub. Rated medium severity (CVSS 5.4), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Mastodon is a free, open-source social network server based on ActivityPub. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Allocation of Resources Without Limits vulnerability could allow attackers to exhaust system resources through uncontrolled allocation.
Mastodon is a free, open-source social network server based on ActivityPub. Rated critical severity (CVSS 9.9), this vulnerability is remotely exploitable, low attack complexity. This Path Traversal vulnerability could allow attackers to access files and directories outside the intended path.
Mastodon is a free, open-source social network server based on ActivityPub. Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Cross-Site Scripting (XSS) vulnerability could allow attackers to inject malicious scripts into web pages viewed by other users.
Mastodon is a free, open-source social network server based on ActivityPub Mastodon allows configuration of LDAP for authentication. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available.
Mastodon through 4.0.2 allows attackers to cause a denial of service (large Sidekiq pull queue) by creating bot accounts that follow attacker-controlled accounts on certain other servers associated. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Improper Restriction of Excessive Authentication Attempts in GitHub repository mastodon/mastodon prior to 4.0.0. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
app/models/user.rb in Mastodon before 3.5.0 allows a bypass of e-mail restrictions. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Sign-up restriction bypass in Mastodon (self-hosted ActivityPub social server) before v4.5.9, v4.4.16, and v4.3.22 allows remote attackers to register accounts on instances that restrict registration by e-mail domain. Because Mastodon validates addresses but does not restrict characters that downstream mail servers interpret differently, a crafted address can pass the allow/deny-list check while ultimately delivering mail to a domain the operator intended to block. No public exploit identified at time of analysis, and EPSS is very low (0.04%), but SSVC rates the flaw automatable with partial technical impact.
Mastodon versions 4.5.x before 4.5.8 and 4.4.x before 4.4.15 allow unauthenticated attackers with prior knowledge of a quote to prevent its correct processing on a target server, resulting in limited integrity and availability impact. The vulnerability exploits timing and knowledge of ActivityPub quote structures to disrupt social content distribution. Patches are available in Mastodon 4.5.8 and 4.4.15; versions 4.3 and earlier are unaffected due to lack of quote support.
Mastodon prior to versions 4.5.8, 4.4.15, and 4.3.21 contains an unauthenticated Open Redirect vulnerability in the `/web/*` route that allows remote attackers to redirect users to arbitrary external domains via specially URL-encoded path segments. An attacker can exploit this to conduct phishing attacks or steal OAuth credentials by crafting malicious links that bypass Rails path normalization through URL-encoded slashes (%2F). No public exploit code or active exploitation has been confirmed at time of analysis.
Mastodon servers with the experimental FASP feature enabled are vulnerable to Server-Side Request Forgery (SSRF) attacks, allowing unauthenticated attackers to register accounts with arbitrary base URLs that force the server to make requests to internal or local addresses. While attackers cannot control the full request path or view responses, this exposure of internal systems to external manipulation could facilitate reconnaissance or attacks on backend infrastructure. Affected versions are 4.4.0-4.4.13 and 4.5.0-4.5.6; a patch is available.
Unauthenticated attackers can bypass FASP administrator approval in Mastodon 4.4.0-4.4.13 and 4.5.0-4.5.6 to subscribe to account events and request content backfill, affecting only servers with the experimental FASP feature enabled. While individual requests cause minor information disclosure of publicly available URIs, repeated exploitation enables denial-of-service attacks. A patch is available to address this authorization bypass.
Mastodon versions prior to 4.3.19, 4.4.13, and 4.5.6 are vulnerable to web cache poisoning in ActivityPub endpoints when AUTHORIZED_FETCH is enabled, allowing cached responses to be served across different user contexts regardless of request signing. An attacker could exploit this to view content intended for non-blocked accounts or cause blocked users to receive empty responses meant for them, potentially bypassing access controls. No patch is currently available for affected deployments.
Mastodon is a free, open-source social network server based on ActivityPub. [CVSS 6.5 MEDIUM]
Mastodon prior to versions 4.5.5, 4.4.12, and 4.3.18 lacks input validation on list and filter names, allowing authenticated users to create arbitrarily long strings that consume excessive server resources and storage. A local attacker can exploit this to degrade system performance or render their own web interface unusable, though no patch is currently available for affected versions.
Mastodon is a free, open-source social network server based on ActivityPub. [CVSS 7.5 HIGH]
Suspended remote users in Mastodon can bypass suspension restrictions and have their posts appear in timelines through boosting and post processing logic errors. This affects all Mastodon versions for older posts, with additional bypass capabilities in versions 4.5.0-4.5.4, 4.4.5-4.4.11, 4.3.13-4.3.17, and 4.2.26-4.2.29, allowing suspended users to inject new content into the system. No patch is currently available for this integrity issue.
Mastodon versions prior to 4.3.17, 4.4.11, and 4.5.4 fail to validate ownership when retrieving severed relationship lists, allowing any authenticated user to enumerate all lost followers and followed accounts across all severance events. This information disclosure vulnerability affects multi-user Mastodon instances where relationship changes due to moderation actions are visible to unauthorized users. An attacker with a local account can systematically access relationship data they should not have permission to view.
Mastodon's IP address filtering bypass (CWE-918) permits attackers to craft requests using unblocked IP ranges to reach local and loopback services, potentially exposing private resources and internal APIs. An unauthenticated remote attacker can exploit incomplete private address range validation in Mastodon instances to perform Server-Side Request Forgery (SSRF) attacks. Patched versions 4.5.4, 4.4.11, 4.3.17, and 4.2.29 are available.
Mastodon is a free, open-source social network server based on ActivityPub Mastodon which facilitates LDAP configuration for authentication. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Allocation of Resources Without Limits vulnerability could allow attackers to exhaust system resources through uncontrolled allocation.
Mastodon is a self-hosted, federated microblogging platform. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Exposure of Sensitive Information vulnerability could allow attackers to access sensitive data that should not be disclosed.
Mastodon is a self-hosted, federated microblogging platform. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Allocation of Resources Without Limits vulnerability could allow attackers to exhaust system resources through uncontrolled allocation.
In Mastodon 4.1.6, API endpoint rate limiting can be bypassed by setting a crafted HTTP request header. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable. No vendor patch available.
Mastodon is a self-hosted, federated microblogging platform. Rated high severity (CVSS 8.2), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Missing Authorization vulnerability could allow attackers to access resources or perform actions without proper authorization checks.
Mastodon is a free, open-source social network server based on ActivityPub. Rated high severity (CVSS 7.7), this vulnerability is remotely exploitable, low attack complexity. This Unrestricted File Upload vulnerability could allow attackers to upload malicious files that can be executed on the server.
Mastodon is a free, open-source social network server based on ActivityPub. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity.
Mastodon is a free, open-source social network server based on ActivityPub. Rated high severity (CVSS 7.4), this vulnerability is remotely exploitable, no authentication required. Public exploit code available.
Mastodon is a free, open-source social network server based on ActivityPub Mastodon allows configuration of LDAP for authentication. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Mastodon is a free, open-source social network server based on ActivityPub. Rated medium severity (CVSS 5.4), this vulnerability is remotely exploitable, low attack complexity. This Cross-Site Scripting (XSS) vulnerability could allow attackers to inject malicious scripts into web pages viewed by other users.
Mastodon is a free, open-source social network server based on ActivityPub. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Mastodon is a free, open-source social network server based on ActivityPub. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Mastodon is a free, open-source social network server based on ActivityPub. Rated medium severity (CVSS 5.4), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Mastodon is a free, open-source social network server based on ActivityPub. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Allocation of Resources Without Limits vulnerability could allow attackers to exhaust system resources through uncontrolled allocation.
Mastodon is a free, open-source social network server based on ActivityPub. Rated critical severity (CVSS 9.9), this vulnerability is remotely exploitable, low attack complexity. This Path Traversal vulnerability could allow attackers to access files and directories outside the intended path.
Mastodon is a free, open-source social network server based on ActivityPub. Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Cross-Site Scripting (XSS) vulnerability could allow attackers to inject malicious scripts into web pages viewed by other users.
Mastodon is a free, open-source social network server based on ActivityPub Mastodon allows configuration of LDAP for authentication. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available.
Mastodon through 4.0.2 allows attackers to cause a denial of service (large Sidekiq pull queue) by creating bot accounts that follow attacker-controlled accounts on certain other servers associated. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Improper Restriction of Excessive Authentication Attempts in GitHub repository mastodon/mastodon prior to 4.0.0. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
app/models/user.rb in Mastodon before 3.5.0 allows a bypass of e-mail restrictions. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity.