CVE-2025-31161

9.8 Known exploited Used in ransomware

CrushFTP Authentication Bypass Vulnerability

CVSS: 9.8, critical critical CVSS v3.1
EPSS, next 30 days: 100% higher than 99.9% of scored CVEs
Exploitation: Confirmed in the wild
Published: 3 Apr 2025a year ago

Known exploited

CISA added this to the Known Exploited Vulnerabilities Catalog on 7 Apr 2025 and links it to ransomware activity. US federal agencies had to remediate by 28 Apr 2025, a deadline that has passed.

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.

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.

Details

Vendor: CrushFTP
Product: CrushFTP
Weakness: CWE-305 (opens in a new tab)
Status: Analyzed
Updated: 17 Jun 2026
Assigner: cve@mitre.org

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References 10

Exploit code 4

Advisories 4

Other references 2

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other CrushFTP CVEs

Every CrushFTP CVE we hold

Same vendor in what we hold, not a known link between the flaws.

CVE-2025-54309 CrushFTP Unprotected Alternate Channel Vulnerability KEV EPSS 95% 9.8, critical
CVE-2024-4040 CrushFTP VFS Sandbox Escape Vulnerability KEV EPSS 100% 10, critical

Beyond this page

Is CVE-2025-31161 in your network?

This page tells you how dangerous CVE-2025-31161 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

CVE-2025-31161 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.

EXYS7600 OCELOT

Find it before attackers do

Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2025-31161 comes with the devices to patch.
Learn more about EXYS7600 OCELOT
EXYS7950 KONDRA

Detect it if it's exploited

Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.
Learn more about EXYS7950 KONDRA

Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.