Loading vulnerability…
CVE-2021-3773 is an information disclosure vulnerability in netfilter, where a network-connected attacker can infer OpenVPN connection endpoint information. This could be leveraged to identify the IP addresses and ports used by OpenVPN connections, potentially exposing them to further targeted attacks.
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
If you can’t patch tonight, do this now.
Patch, then assume compromise.
1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
This repository contains a Python proof-of-concept exploit (PoC.py) for CVE-2021-3773, a vulnerability in OpenVPN servers using Netfilter for NAT. The exploit leverages the 'Port Shadow' technique to deanonymize VPN users or maintain a man-in-the-middle (MITM) position by sending crafted UDP packets to the VPN server. The script is configurable for the attacker's, victim's, and VPN server's IP addresses and uses threading for efficient scanning of ephemeral ports. It logs attack activities to a file (attack_log.txt). The README provides context, usage instructions, and ethical guidelines. The exploit is not part of a framework and is a standalone PoC, requiring manual configuration and execution. The main attack vector is network-based, targeting OpenVPN servers vulnerable to CVE-2021-3773.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
7 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Linux kernel NAT/netfilter port-validation flaw affecting OpenVPN clients.
Linux kernel NATD and Netfilter port-validation flaw affecting OpenVPN clients.
Linux kernel NATD/Netfilter port-validation flaw affecting OpenVPN clients.
Linux kernel NATD/netfilter port-validation flaw affecting OpenVPN clients.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.