CVE-2025-31161
This CVE is being exploited. Apply the vendor fix, or take the service off the internet until you can, then check your logs for attempts.
What it is
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.
Live exploitation on the huntback network (30 days)
Detection
Evidence
Confirmed exploited. Our decoys saw 3 exploitation attempts in the last 14 days; CISA added it to KEV 584 days ago.
Last attempt. 9 attempts on our decoys, 3 in the last 14 days
First exploitation attempt on our decoys
Added to CISA Known Exploited Vulnerabilities
Published
Exploit code published (ExploitDB)
Nuclei detection template available
Observed: our own decoys saw it. Reported: CISA, the vendor or another named source says so. Weaponised: public exploit code or a scanner template exists. Methodology
Questions
Is CVE-2025-31161 being exploited in the wild?
Yes. The huntback decoy network captured 9 exploitation attempts from 2 distinct source IPs; the most recent was on 2026-11-10. It is also in the CISA KEV catalogue.
Can CVE-2025-31161 be detected on the network?
Yes. huntback carries a network signature for CVE-2025-31161, so attempts against a decoy are tagged in real time.
How huntback helps
Deploy a decoy that emulates Crushftp and you will see every attempt at this CVE the moment it lands, with the full payload, the attacker's infrastructure, and any stage-2 loader. Then huntback can scan the attacker back.
Related
NVD record → Browse all CVEs → Live malware and C2 finds → Novel-attack discovery → Deploy a decoy →API
This record, with its evidence timeline, as JSON:
curl -H "X-API-Key: $HUNTBACK_KEY" https://app.huntback.io/api/v1/evidence/CVE-2025-31161