How severe is CVE-2025-31161?

CVE-2025-31161 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2025-31161?

Affected package information for CVE-2025-31161 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2025-31161?

No fixed version has been published for CVE-2025-31161 yet. Monitor the advisory for updates, apply mitigations recommended by the vendor, and use O3 Security to track when a fix becomes available in your stack.

Is CVE-2025-31161 actively exploited in the wild?

Yes. There are 3 known exploit references for CVE-2025-31161, including 1 documented proof-of-concept exploit on Exploit-DB. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2025-31161?

CVE-2025-31161 has an EPSS (Exploit Prediction Scoring System) score of 88.9%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2025-31161 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2025-31161 (CrushFTP Authentication Bypass Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2025-04-07. CISA required all US federal civilian agencies to remediate this vulnerability by 2025-04-28. The required action was: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. This CVE has been used in known ransomware campaigns. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2025-31161?

CVE-2025-31161 is classified as CWE-305 (CWE-305). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Which products and versions are affected by CVE-2025-31161?

CVE-2025-31161 affects crushftp crushftp. Check the affected-products list on this page against your deployed version to confirm exposure.

Is there exploit tooling available for CVE-2025-31161?

A Nuclei detection template exists for CVE-2025-31161, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2025-31161 published, and has it been updated?

CVE-2025-31161 was published on April 3, 2025 and was last updated on October 31, 2025. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2025-31161: Crushftp CWE-305 (Critical 9.8)

EPSS Exploitation Probability

via FIRST.org ↗

88.9%probability of exploitation in next 30 days

Very High Risk100th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

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.

Affected Products

1 product · 2 configurations

Application

crushftpcrushftp

≥ 11.0.0 && < 11.3.1

range

Frequently Asked Questions

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 f

O3 Security · Impact-Aware SCA

Is CVE-2025-31161 in your stack?

O3 detects CVE-2025-31161 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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