CVE-2025-54879

Estado: AnalizadaAlta (7.5)—

Mastodon is a free, open-source social network server based on ActivityPub Mastodon which facilitates LDAP configuration for authentication. In versions 3.1.5 through 4.2.24, 4.3.0 through 4.3.11 and 4.4.0 through 4.4.3, Mastodon's rate-limiting system has a critical configuration error where the email-based throttle for confirmation emails incorrectly checks the password reset path instead of the confirmation path, effectively disabling per-email limits for confirmation requests.

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This allows attackers to bypass rate limits by rotating IP addresses and send unlimited confirmation emails to any email address, as only a weak IP-based throttle (25 requests per 5 minutes) remains active. The vulnerability enables denial-of-service attacks that can overwhelm mail queues and facilitate user harassment through confirmation email spam. This is fixed in versions 4.2.24, 4.3.11 and 4.4.3.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Puntuación base: 7.5

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.56%
Percentil entre todas las CVEs puntuadas: 45
Fecha de la puntuación: 5/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1190 Exploit Public-Facing Applicationinitial access75 %
Impacto principalT1499.004 Application or System Exploitationimpact85 %
Impacto secundarioT1499 Endpoint Denial of Serviceimpact75 %

AV:N/AC:L/PR:N sin UI:N indica explotación remota sin autenticación ni interacción (T1190). El bypass de rate-limiting permite DoS por flooding de peticiones SMTP (T1499.004), explotando error de configuración en throttle de emails de confirmación.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Filter Network Traffic Vulnerability Scanning Privileged Account Management Network Segmentation Limit Access to Resource Over Network Application Isolation and Sandboxing

Tecnologías afectadas (1)

Joinmastodon — Mastodon

CWE

CWE-770

Referencias

JSON original (NVD)

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  "cveTags": [],
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      "value": "Mastodon is a free, open-source social network server based on ActivityPub Mastodon which facilitates LDAP configuration for authentication. In versions 3.1.5 through 4.2.24, 4.3.0 through 4.3.11 and 4.4.0 through 4.4.3, Mastodon's rate-limiting system has a critical configuration error where the email-based throttle for confirmation emails incorrectly checks the password reset path instead of the confirmation path, effectively disabling per-email limits for confirmation requests. This allows attackers to bypass rate limits by rotating IP addresses and send unlimited confirmation emails to any email address, as only a weak IP-based throttle (25 requests per 5 minutes) remains active. The vulnerability enables denial-of-service attacks that can overwhelm mail queues and facilitate user harassment through confirmation email spam. This is fixed in versions 4.2.24, 4.3.11 and 4.4.3."
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      "value": "Mastodon es un servidor de red social gratuito y de código abierto basado en ActivityPub Mastodon, que facilita la configuración LDAP para la autenticación. En las versiones 3.1.5 a 4.2.24, 4.3.0 a 4.3.11 y 4.4.0 a 4.4.3, el sistema de limitación de velocidad de Mastodon presenta un error crítico de configuración: la limitación basada en correo electrónico para los correos de confirmación verifica incorrectamente la ruta de restablecimiento de contraseña en lugar de la de confirmación, lo que desactiva los límites por correo electrónico para las solicitudes de confirmación. Esto permite a los atacantes eludir las limitaciones de velocidad rotando las direcciones IP y enviar correos de confirmación ilimitados a cualquier dirección, ya que solo permanece activa una limitación débil basada en IP (25 solicitudes cada 5 minutos). Esta vulnerabilidad permite ataques de denegación de servicio que pueden saturar las colas de correo y facilitar el acoso a los usuarios mediante correos de confirmación no deseados. Esto se ha corregido en las versiones 4.2.24, 4.3.11 y 4.4.3."
    }
  ],
  "lastModified": "2026-06-17T09:40:51.323",
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