Assessment
Why it matters
CISA lists this vulnerability as known to be exploited; exploitation is confirmed; EPSS is 99.9%; technical severity is CVSS 9.8.
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.
Who should care
- Teams operating Crushftp
- Vulnerability and exposure management teams
- Security operations teams monitoring exploitation activity
Response plan
What I would do
- Confirm whether Crushftp is present in the environment.
- Identify affected versions and establish whether vulnerable services are exposed or reachable.
- Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- Review relevant security telemetry for evidence of attempted or successful exploitation.
- Document the remediation decision and track it to verified completion.
Vendor remediation
Patch and remediation links
Use the vendor source below to confirm the correct fixed version, package or mitigation for your affected product.
Technical details
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CWE
- CWE-305
- Affected versions
- Crushftp Crushftp (Start Including: 11.0.0, End Excluding: 11.3.1)
- Published
- 3 April 2025
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
Signal timeline
- CVE published
- Added to CISA KEV
- Latest EPSS score: 99.9%
- Signal calculated at 88
External references
- Government advisory from www.cisa.gov
- Exploit information from attackerkb.com
- Exploit information from projectdiscovery.io
- Technical reference from www.darkreading.com
- Exploit information from www.huntress.com
- Technical reference from www.infosecurity-magazine.com
- Exploit information from www.vicarius.io
- Mitigation guidance from www.vicarius.io
- Vendor advisory from crushftp.com
- Third-party advisory from outpost24.com