Threat Intelligence / CVE / CVE-2025-31161

CVE-2025-31161 — Crushftp

CISA KEVRansomware
CVSS v3.1 9.8 (CRITICAL) · EPSS 86.2% (higher than 99.4% of all scored CVEs) · Priority 10/10 · Published 2025-04-03

As of 2025-10-31, CVE-2025-31161 is a CRITICAL-severity vulnerability in Crushftp, CVSS v3.1 9.8, EPSS 86.2% (99.4th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-04-07), with a US federal remediation deadline of 2025-04-28, and CISA links it to known ransomware campaigns. Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2025-31161, most recently “Storm-1175 Medusa Ransomware Zero-Day Exploitation Campaign (CVE-2026-23760, CVE-2025-10035)”.

Last updated: 2025-10-31

What is CVE-2025-31161?

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.

The record classifies CVE-2025-31161 under weakness classes CWE-305, NVD-CWE-Other. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 528 days ago.

Severity and exploitation probability

CVSS v3.1 base score
9.8 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (FIRST)
86.2% probability of exploitation in the next 30 days, higher than 99.4% of all scored CVEs
CISA KEV
Listed since 2025-04-07, federal remediation deadline 2025-04-28 — used in known ransomware campaigns
Threadlinqs priority
10/10 — CISA lists it as used in ransomware, which Threadlinqs scores at the maximum
Published
2025-04-03, last modified 2025-10-31

Is CVE-2025-31161 being exploited?

CISA added CVE-2025-31161 to the Known Exploited Vulnerabilities catalog on 2025-04-07, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2025-04-28 under BOD 22-01. CISA flags the vulnerability as one used in known ransomware campaigns. It currently carries a trending score of 40 in the Threadlinqs vulnerability feed.

Affected products and versions

How to fix CVE-2025-31161

Vendor advisory: https://crushftp.com/crush11wiki/Wiki.jsp?page=Update#section-Update-VulnerabilityInfo. Because CVE-2025-31161 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2025-04-28. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2025-31161

1 tracked threat in the Threadlinqs corpus references CVE-2025-31161, either in the campaign’s CVE list or as an indicator on the campaign record.

Sources

Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.

Full detection coverage & IOCs for threats exploiting CVE-2025-31161 are available via the Threadlinqs MCP server (Purple tier). View plans →

← all vulnerabilities · Markdown version · Threadlinqs Intelligence