// For flags

CVE-2025-31161

CrushFTP Authentication Bypass Vulnerability

Severity Score

9.8
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

1
*Multiple Sources

Exploited in Wild

Yes
*KEV

Decision

Act
*SSVC
Descriptions

CrushFTP 10 before 10.8.4 and 11 before 11.3.1 allows authentication bypass and takeover of the crushadmin account (unless a DMZ proxy instance is used), as exploited in the wild in March and April 2025, aka "Unauthenticated HTTP(S) port access." A race condition exists in the AWS4-HMAC (compatible with S3) authorization method of the HTTP component of the FTP server. The server first verifies the existence of the user by performing a call to login_user_pass() with no password requirement. This will authenticate the session through the HMAC verification process and up until the server checks for user verification once more. The vulnerability can be further stabilized, eliminating the need for successfully triggering a race condition, by sending a mangled AWS4-HMAC header. By providing only the username and a following slash (/), the server will successfully find a username, which triggers the successful anypass authentication process, but the server will fail to find the expected SignedHeaders entry, resulting in an index-out-of-bounds error that stops the code from reaching the session cleanup. Together, these issues make it trivial to authenticate as any known or guessable user (e.g., crushadmin), and can lead to a full compromise of the system by obtaining an administrative account.

CrushFTP 10 anterior a la 10.8.4 y 11 anterior a la 11.3.1 permite omitir la autenticación y tomar el control de la cuenta crushadmin (a menos que se utilice una instancia de proxy DMZ), como se explotó en marzo y abril de 2025, también conocido como "Acceso al puerto HTTP(S) sin autenticar". Existe una condición de ejecución en el método de autorización AWS4-HMAC (compatible con S3) del componente HTTP del servidor FTP. El servidor verifica primero la existencia del usuario mediante una llamada a login_user_pass() sin necesidad de contraseña. Esto autenticará la sesión mediante el proceso de verificación HMAC hasta que el servidor vuelva a verificar la verificación del usuario. La vulnerabilidad se puede estabilizar aún más, eliminando la necesidad de activar una condición de ejecución, mediante el envío de un encabezado AWS4-HMAC alterado. Al proporcionar únicamente el nombre de usuario y una barra diagonal (/), el servidor encontrará un nombre de usuario, lo que activará la autenticación anypass. Sin embargo, no encontrará la entrada SignedHeaders esperada, lo que generará un error de indexación fuera de los límites que impedirá que el código complete la limpieza de la sesión. En conjunto, estos problemas dificultan la autenticación con cualquier usuario conocido o indeterminado (p. ej., crushadmin) y pueden comprometer por completo el sistema al obtener una cuenta administrativa.

CrushFTP contains an authentication bypass vulnerability in the HTTP authorization header that allows a remote unauthenticated attacker to authenticate to any known or guessable user account (e.g., crushadmin), potentially leading to a full compromise.

*Credits: Kristian Varnai, Outpost24, Marcus White, Outpost24
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Attack Vector
Network
Attack Complexity
Low
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete
* Common Vulnerability Scoring System
SSVC
  • Decision:Act
Exploitation
Active
Automatable
Yes
Tech. Impact
Total
* Organization's Worst-case Scenario
Timeline
  • 2025-03-27 CVE Reserved
  • 2025-04-03 CVE Published
  • 2025-04-07 CVE Updated
  • 2025-04-07 Exploited in Wild
  • 2025-04-09 First Exploit
  • 2025-04-15 EPSS Updated
  • 2025-04-28 KEV Due Date
CWE
  • CWE-305: Authentication Bypass by Primary Weakness
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
CrushFTP
Search vendor "CrushFTP"
CrushFTP
Search vendor "CrushFTP" for product "CrushFTP"
>= 10.0.0 < 10.8.4
Search vendor "CrushFTP" for product "CrushFTP" and version " >= 10.0.0 < 10.8.4"
en
Affected
CrushFTP
Search vendor "CrushFTP"
CrushFTP
Search vendor "CrushFTP" for product "CrushFTP"
>= 11.0.0 < 11.3.1
Search vendor "CrushFTP" for product "CrushFTP" and version " >= 11.0.0 < 11.3.1"
en
Affected