Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2025-31161 is a critical-severity Authentication Bypass by Primary Weakness (CWE-305) vulnerability in Crushftp Crushftp. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 0.0% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to IA-2 (Identification and Authentication (Organizational Users)) and IA-8 (Identification and Authentication (Non-organizational Users)) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CrushFTP versions 10 before 10.8.4 and 11 before 11.3.1 contain an authentication bypass vulnerability in the HTTP component of the FTP server. The flaw stems from a race condition in the AWS4-HMAC authorization method, which is compatible with S3 storage. The server initially calls login_user_pass() without requiring a password to verify user existence, allowing session authentication via HMAC before a second verification check occurs. This can be stabilized by supplying a mangled AWS4-HMAC header containing only a username followed by a slash, which triggers anypass authentication while producing an index-out-of-bounds error that prevents session cleanup.
Unauthenticated remote attackers can exploit the issue over HTTP or HTTPS to impersonate any known or guessable account, including the crushadmin administrative user, unless a DMZ proxy instance is deployed. Successful exploitation grants full administrative control and can lead to complete system compromise. The vulnerability carries a CVSS score of 9.8 and was observed being exploited in the wild during March and April 2025.
Vendor guidance and public advisories direct administrators to upgrade immediately to CrushFTP 10.8.4 or 11.3.1. The references also note that the bypass is mitigated when a DMZ proxy configuration is already in place, and they provide additional context on detection and post-exploitation indicators.
The EPSS score has reached a peak of 0.9011 with a current value of 0.8894, reflecting sustained exploitation interest following disclosure.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-9910
Vulnerability Data
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…
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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.
- CWE(s)
- KEV Date Added
- 07 April 2025
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 5 hardening rules · 3 OS baselines
V6.4.3V7.2.4
Mitigating Controls (NIST 800-53 r5) AI
Requires unique identification and authentication of users, structurally blocking bypass of the mechanism.
Requires unique identification and authentication of non-organizational users, blocking bypass paths.
Enforces approved authorizations so a bypass weakness cannot be exploited to reach resources.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure development practices throughout the SDLC prevent the primary weaknesses that enable authentication bypass.
Strong authentication mechanisms and policy enforcement directly reduce bypass opportunities arising from implementation flaws.
Identifying and recording vulnerabilities catches the primary weaknesses that allow authentication bypass.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect authentication bypass conditions before deployment.
Secure development lifecycle reduces likelihood of introducing bypass flaws during implementation.
Secure coding practices help prevent the primary weakness that enables authentication bypass.
Information access restriction complements authentication by limiting what can be reached even if bypass occurs.
Secure authentication mechanisms directly address bypass risks in the implemented authentication process.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Ubuntu 22.04 (1 rule)
- V-260470 Ubuntu 22.04 LTS, when booted, must require authentication upon booting into single-user and maintenance modes. prevents CWE-305
Ubuntu 24.04 (1 rule)
- V-270675 Ubuntu 24.04 LTS when booted must require authentication upon booting into single-user and maintenance modes. prevents CWE-305