CrushFTP contains an authentication bypass (CWE-305) in its handling of the HTTP authorization header, allowing crafted header values to grant access without valid credentials. A remote, unauthenticated attacker who can reach the server's HTTP/HTTPS interface can use this flaw to authenticate as any known or guessable account, such as the built-in crushadmin user. With administrative access, the attacker can typically achieve full compromise of the file-transfer server, including access to hosted files and user accounts. Any organization running CrushFTP is affected, with internet-exposed instances at the highest risk. The flaw is being actively exploited: it was added to CISA's KEV on 2025-04-07 with known ransomware use, and EPSS assigns it a 100% probability of exploitation within 30 days.
What to do: Upgrade to the vendor's fixed releases (10.8.0 for the 10.x line and 11.3.1 for the 11.x line, per vendor advisories); federal agencies must follow BOD 22-01 timelines or discontinue use if mitigations are unavailable. Until patched, restrict network access to the CrushFTP HTTP/HTTPS interface and audit authentication logs for unexpected logins to privileged accounts such as crushadmin. Given confirmed ransomware use, treat internet-exposed instances as actively targeted and verify there are no signs of prior compromise after patching.
Affected
CrushFTP
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Estimated exposure
moderate≈5,000–10,000 internet-exposed CrushFTP servers (public scan counts), with additional uncounted internal enterprise deployments — Public internet-wide scan services showed several thousand exposed CrushFTP instances at the time of the April 2025 KEV listing, and enterprise file-transfer deployments commonly sit behind the firewall as well, so total installations…
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
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.
CISA Known Exploited Vulnerability
Affected
CrushFTP CrushFTP
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.
FBI and Lumen disrupted QTFY's QScan and QTRouter botnet platforms used by Chinese state-sponsored hackers to conceal intrusions into U.S. agencies.
The U.S. DoJ announced court-authorized seizure of domains behind QScan and QTRouter, operated by the Chinese state-sponsored group QTFY and employed by Nanjing Xinjiuwei Network Technology Company. QTFY has been active since May 2018 and targeted NASA, the Federal Reserve, the Department of Energy, DoJ, HHS, NIH, the U.S. Senate, and academic institutions. QScan exploits vulnerable IoT devices, feeding them into QTRouter, an OpenWrt-based proxy obfuscation network likened to an operational relay box (ORB) that masks attack origins. The group exploited zero-days such as Ivanti CSA flaws CVE-2024-8190, CVE-2024-8963, and CVE-2024-9380, plus numerous N-days, and maintained persistence with RATs, web shells, and legitimate credentials.
Microsoft reports China-linked ransomware group Storm-1175 switched from Medusa to a new C++ strain, StormEncryptor, likely exploiting N-able flaw CVE-2026-18577.
Microsoft Threat Intelligence reports that the financially motivated, China-linked group Storm-1175 began deploying a new ransomware strain called StormEncryptor on August 2, 2026, replacing its previous Medusa ransomware. StormEncryptor is written in C++, appends the .encrypted extension to files, and drops a !!!README_FIRST!!!.txt ransom note in each scanned directory. Microsoft assesses the group is likely exploiting CVE-2026-18577, an authentication bypass in N-able disclosed on August 2, 2026 and added to CISA's Known Exploited Vulnerabilities catalog the next day. Since 2023, Storm-1175 has exploited more than 16 vulnerabilities in products including Microsoft Exchange, Ivanti, ConnectWise ScreenConnect, JetBrains TeamCity, SimpleHelp, CrushFTP, and GoAnywhere MFT, often moving from initial access to data theft and ransomware deployment within days.