Hackers have started to exploit a critical remote code execution vulnerability in Wing FTP Server just one day after technical details on the flaw became public.

The observed attack ran multiple enumeration and reconnaissance commands followed by establishing persistence by creating new users.

The exploited Wing FTP Server vulnerability is tracked as CVE-2025-47812 and received the highest severity score. It is a combination of a null byte and Lua code injection that allows remote a unauthenticated attacker to execute code with the highest privileges on the system (root/SYSTEM).

Wing FTP Server is a powerful solution for managing secure file transfers that can execute Lua scripts, which is widely used in enterprise and SMB environments.

On June 30, security researcher Julien Ahrens published a technical write-up for CVE-2025-47812, explaining that the flaw stems from unsafe handling of null-terminated strings in C++ and improper input sanitization in Lua.

The researcher demonstrated how a null byte in the username field could bypass authentication checks and enable Lua code injection into session files.

When those files are subsequently executed by the server, it is possible to achieve arbitrary code execution as root/SYSTEM.

Along with CVE-2025-47812, the researcher presented another three flaws in Wing FTP:

• CVE-2025-27889 – allows exfiltrating user passwords via a crafted URL if the user submits a login form, due to unsafe inclusion of the password in a JavaScript variable (location)
• CVE-2025-47811 – Wing FTP runs as root/SYSTEM by default, with no sandboxing or privilege drop, making RCEs far more dangerous
• CVE-2025-47813 – supplying an overlong UID cookie reveals file system paths

All the flaws impact Wing FTP versions 7.4.3 and earlier. The vendor fixed the issues by releasing version 7.4.4 on May 14, 2025, except for CVE-2025-47811, which was deemed unimportant.

Threat researchers at managed cybersecurity platform Huntress created a proof-of-concept exploit for CVE-2025-47812 and show in the video below how hackers could leverage it in attacks:

Huntress researchers found that on July 1st, a day after technical details for CVE-2025-47812 appeared, at least one attacker exploited the vulnerability at one of their customers.

The attacker sent malformed login requests with null-byte-injected usernames, targeting ‘loginok.html.’ These inputs created malicious session .lua files that injected Lua code into the server.

The injected code was designed to hex-decode a payload and execute it via cmd.exe, using certutil to download malware from a remote location and execute it.

Huntress says that the same Wing FTP instance was targeted by five distinct IP addresses within a short time frame, potentially indicating mass-scanning and exploitation attempts by several threat actors.

The commands observed in these attempts were for reconnaissance, obtaining persistence in the environment, and data exfiltration using the cURL tool and webhook endpoint.

The hacker failed the attack “maybe due to their unfamiliarity with them, or because Microsoft Defender stopped part of their attack,” Huntress says. Nevertheless, the researchers observed clear exploitation of the critical Wing FTP Server vulnerability.

Even if Huntress observed failed attacks at their customers, hackers are likely to scan for reachable Wing FTP instances and try to take advantage of vulnerable servers.

Companies are strongly advised to upgrade to version 7.4.4 of the product as soon as possible.

If switching to a newer, secure version is not possible, the researchers’ recommendation is to disable or restrict HTTP/HTTPs access to the Wing FTP web portal, disable anonymous logins, and monitor the session directory for suspicious additions.

A maximum severity remote code execution (RCE) vulnerability has been discovered impacting all versions of Apache Parquet up to and including 1.15.0.

The problem stems from the deserialization of untrusted data that could allow attackers with specially crafted Parquet files to gain control of target systems, exfiltrate or modify data, disrupt services, or introduce dangerous payloads such as ransomware.

The vulnerability is tracked under CVE-2025-30065 and has a CVSS v4 score of 10.0. The flaw was fixed with the release of Apache version 1.15.1.

It should be noted that to exploit this flaw, threat actors must convince someone to import a specially crafted Parquet file.

Severe threat to “big data” environments

Apache Parquet is an open-source, columnar storage format designed for efficient data processing. Unlike row-based formats (like CSV), Parquet stores data by columns, which makes it faster and more space-efficient for analytical workloads.

It is widely adopted across the data engineering and analytics ecosystem, including big data platforms like Hadoop, AWS, Amazon, Google, and Azure cloud services, data lakes, and ETL tools.

Some large companies that use Parquet include Netflix, Uber, Airbnb, and LinkedIn.

The security problem in Parquet was disclosed on April 1, 2025, following a responsible disclosure by its finder, Amazon researcher Keyi Li.

“Schema parsing in the parquet-avro module of Apache Parquet 1.15.0 and previous versions allows bad actors to execute arbitrary code,” warned the short bulletin published on Openwall.

“Users are recommended to upgrade to version 1.15.1, which fixes the issue.”

A separate bulletin by Endor Labs highlights the risk of CVE-2025-30065 exploitation more clearly, warning that the flaw can impact any data pipelines and analytics systems that import Parquet files, with the risk being significant for files sourced from external points.

Endor Labs believes the problem was introduced in Parquet version 1.8.0, though older releases might also be impacted. The firm suggests coordinated checks with developers and vendors to determine what Praquet versions are used in production software stacks.

“If an attacker tricks a vulnerable system into reading a specially crafted Parquet file, they could gain remote code execution (RCE) on that system,” warns Endor Labs.

However, the security firm avoids over-inflating the risk by including the note, “Despite the frightening potential, it’s important to note that the vulnerability can only be exploited if a malicious Parquet file is imported.”

That being said, if upgrading to Apache Parquet 1.15.1 immediately is impossible, it is suggested to avoid untrusted Parquet files or carefully validate their safety before processing them. Also, monitoring and logging on systems that handle Parquet processing should be increased.

Although no active exploitation has been discovered yet, the risk is high due to the flaw’s severity and the widespread use of Parquet files in big data applications.

Administrators of impacted systems are recommended to upgrade to Parquet version 1.15.1, which addresses CVE-2025-30065, as soon as possible.