CVE-2025-31161
CrushFTP Authentication Bypass Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 28 April 2025). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
Description
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 99.97% probability · 100th percentile
- Public exploits
- 1 in Exploit-DB · first 18 May 2025
- CISA KEV
- Listed 7 April 2025 · due 28 April 2025 · used in ransomware campaigns
- Weakness
- CWE-305
- Affected
- crushftp/crushftp
- Source
- cve@mitre.org
EPSS 100.0% since 26 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
CISA notes
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. https://www.crushftp.com/crush11wiki/Wiki.jsp?page=Update ; https://nvd.nist.gov/vuln/detail/CVE-2025-31161
Public exploits (1)
Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.
References
- https://crushftp.com/crush11wiki/Wiki.jsp?page=Update#section-Update-VulnerabilityInfoVendor Advisory
- https://outpost24.com/blog/crushftp-auth-bypass-vulnerability/Third Party Advisory
- https://attackerkb.com/topics/k0EgiL9Psz/cve-2025-2825/rapid7-analysisExploit, Third Party Advisory
- https://projectdiscovery.io/blog/crushftp-authentication-bypassExploit, Third Party Advisory
- https://www.darkreading.com/vulnerabilities-threats/disclosure-drama-clouds-crushftp-vulnerability-exploitationPress/Media Coverage
- https://www.huntress.com/blog/crushftp-cve-2025-31161-auth-bypass-and-post-exploitationExploit, Third Party Advisory
- https://www.infosecurity-magazine.com/news/crushftp-flaw-exploited-disclosure/Press/Media Coverage
- https://www.vicarius.io/vsociety/posts/cve-2025-31161-detect-crushftp-vulnerabilityExploit, Third Party Advisory
- https://www.vicarius.io/vsociety/posts/cve-2025-31161-mitigate-crushftp-vulnerabilityMitigation, Third Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-31161US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.