CrushFTP up to 10.8.3/11.3.0 HTTP login_user_pass authentication bypass

Summaryinfo

A vulnerability was found in CrushFTP up to 10.8.3/11.3.0. It has been classified as critical. This vulnerability affects the function login_user_pass of the component HTTP Component. Performing a manipulation results in authentication bypass. This vulnerability was named CVE-2025-31161. The attack may be initiated remotely. In addition, an exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as critical has been found in CrushFTP up to 10.8.3/11.3.0. This affects the function login_user_pass of the component HTTP Component. The manipulation with an unknown input leads to a authentication bypass vulnerability. CWE is classifying the issue as CWE-305. The authentication algorithm is sound, but the implemented mechanism can be bypassed as the result of a separate weakness that is primary to the authentication error. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at outpost24.com. This vulnerability is uniquely identified as CVE-2025-31161 since 03/27/2025. The exploitability is told to be difficult. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details and a public exploit are known.

The exploit is shared for download at exploit-db.com. It is declared as attacked. The vulnerability scanner Nessus provides a plugin with the ID 233965 (CrushFTP < 11.3.1 Authentication Bypass (CVE-2025-31161) (Direct Check)), which helps to determine the existence of the flaw in a target environment. The CISA Known Exploited Vulnerabilities Catalog lists this issue since 04/07/2025 with a due date of 04/28/2025:

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Upgrading to version 10.8.4 or 11.3.1 eliminates this vulnerability.

The vulnerability is also documented in the databases at Exploit-DB (52295) and Tenable (233965). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

• CrushFTP

Version

• 10.8.0
• 10.8.1
• 10.8.2
• 10.8.3
• 11.0
• 11.1
• 11.2
• 11.3.0

CPE 2.3info

• 🔍
• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍
• 🔍

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion