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.

Previously linked to CVE-2025-2825, this flaw has been exploited in the wild for weeks and a ransomware group is threatening to extort victims. Patch as soon as possible.

The CrushFTP application installed on the remote host is missing a vendor-supplied patch and is affected by an authentication bypass vulnerability:

  - CrushFTP versions 10.0.0 through 10.8.3 and 11.0.0 through 11.3.0 are affected by a vulnerability that may result     in unauthenticated access. Remote and unauthenticated HTTP requests to CrushFTP may allow attackers to gain     unauthorized access. (CVE-2025-31161)

CrushFTP versions 10.x before 10.8.3 and 11.x before 11.3.0 are vulnerable to an authentication bypass vulnerability, allowing a remote and unauthenticated user to gain access to the target CrushFTP instance.

ID	Name	Product	Family	Severity
233965	CrushFTP < 11.3.1 Authentication Bypass (CVE-2025-31161) (Direct Check)	Nessus	Web Servers	critical
114684	CrushFTP 10.x < 10.8.3 / 11.x < 11.3.0 Authentication Bypass	Web App Scanning	Component Vulnerability	critical

Detections

Analytics

CVE-2025-31161

critical

Tenable Plugins

critical

critical