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Fencer Intel
critical 9.8

CVE-2025-31161 kev+ ransomware in the critical feed json

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 inst…

published last yr. modified 4mo ago also EUVD-2025-9910

cvss
9.8
version 3.1, CNA
cisa kev
Exploited
added 2025-04-07, used in ransomware
epss
100.0%
EPSS 100.0% chance of exploitation in 30 days, percentile 99.9%
public exploits
1
Exploit-DB, plus a Nuclei check

Summary

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.

Patch / fix

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

  • CrushFTP CrushFTP 10.8.4, 11.3.1

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Timeline

  1. Published
  2. Added to CISA KEV
  3. CISA patch deadline
  4. First public exploit (EDB-52295)
  5. CISA SSVC: exploitation active

Known exploited

Added
last yr.
Patch by
2025-04-28 (last yr.)
Ransomware
Known to be used in ransomware campaigns
Required action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Vendor, product
CrushFTP, CrushFTP
CISA name
CrushFTP Authentication Bypass Vulnerability

Ransomware

Groups reported to have exploited it in intrusions.

  • Kill Ransomware ransomware gang

reported by kennedyslaw.com

Ransomware Vulnerability Matrix by BushidoUK (github.com/BushidoUK/Ransomware-Vulnerability-Matrix), reformatted per CVE. CC BY 4.0

ATT&CK techniques

How it is exploited and what it leads to, in MITRE ATT&CK terms.

  • T1078 Valid Accounts exploitation
  • T1059 Command and Scripting Interpreter primary impact
  • T1136 Create Account primary impact

kev release 2025-07-28, att&ck v16.1. KEV to ATT&CK mappings by the MITRE Center for Threat-Informed Defense (Mappings Explorer, Apache-2.0). © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. Terms of use

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
yes
Technical impact
total
Assessed
last yr.

Exploit prediction

99.97% chance of exploitation in the next 30 days, higher than 99.9% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • EDB-52295 CrushFTP 11.3.1 - Authentication Bypass remote, 2025-05-18
  • Nuclei template CrushFTP - Authentication Bypass nuclei detection template
  • projectdiscovery.io https://projectdiscovery.io/blog/crushftp-authentication-bypass referenced PoC, tagged "exploit" by a source, unverified
  • huntress.com https://www.huntress.com/blog/crushftp-cve-2025-31161-auth-bypass-and-post-exploitation referenced PoC, tagged "exploit" by a source, unverified
  • attackerkb.com https://attackerkb.com/topics/k0EgiL9Psz/cve-2025-2825/rapid7-analysis referenced PoC, tagged "exploit" by a source, unverified
  • vicarius.io https://www.vicarius.io/vsociety/posts/cve-2025-31161-detect-crushftp-vulnerability referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • CrushFTP CrushFTP

Classification

Weakness
  • CWE-305 Authentication Bypass by Primary Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.