VMware ESXi OpenSLP Heap Overflow RCE
CVE-2021-21974 is a heap-overflow vulnerability in the OpenSLP service as used by VMware ESXi. It affects ESXi 7.0 before ESXi70U1c-17325551, ESXi 6.7 before ESXi670-202102401-SG, and ESXi 6.5 before ESXi650-202102101-SG. According to the provided content, a malicious actor on the same network segment as the ESXi host who can reach port 427 can trigger the heap-overflow condition in OpenSLP, potentially leading to remote code execution on the ESXi hypervisor.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
2 valid exploits after Mallory filtered fakes, detection scripts, and README-only repos (1 hidden).
This repository provides a proof-of-concept (PoC) exploit for CVE-2021-21974, a remote code execution vulnerability in the OpenSLP service of VMware ESXi (7.x and earlier). The main exploit script, '2021-21974-POC.py', is a Python 3 program that connects to the target ESXi host on TCP port 427 (the default OpenSLP port) and sends crafted SLP packets to trigger the vulnerability. Upon successful exploitation, it executes a shell command on the target that creates a named pipe and attempts to establish a reverse shell connection back to the attacker's machine at 192.168.0.194:80 using netcat. The repository also includes a README.md with detailed usage instructions, requirements, and mitigation advice, and a requirements.txt listing Python dependencies. The exploit is intended for educational and research purposes only and is not weaponized; the payload IP address must be changed by the user to receive the reverse shell. The attack vector is network-based, requiring only network access to the vulnerable ESXi host.
This repository contains a proof-of-concept (PoC) exploit for CVE-2021-21974, a remote code execution vulnerability in VMware ESXi 6.7.0 (builds 14320388 and 16316930). The main file, '2021-21974-POC.py', is a Python script that targets the Service Location Protocol (SLP) service on port 427 of a vulnerable ESXi host. The exploit crafts and sends a series of SLP protocol messages to trigger the vulnerability, ultimately allowing the attacker to execute arbitrary shell commands on the target system. By default, the payload establishes a reverse shell from the ESXi host to the attacker's machine at 192.168.0.194:80 using a named pipe at /tmp/backpipe. The script is operational and requires the attacker to specify the target's IP address as a command-line argument. The repository also includes a brief README.md describing the exploit's purpose. No detection scripts or framework integration are present; the code is a standalone exploit PoC.
Affected products & vendors
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Recent activity
8 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A specific vulnerability explicitly cited as used by Sea Turtle for exploitation to achieve client code execution.
A heap-overflow vulnerability in VMware ESXi OpenSLP service that allows remote code execution.
A VMware ESXi remote code execution vulnerability referenced as being exploited by the ESXiArgs ransomware campaign for initial access / deployment at scale.
Severe buffer overflow vulnerability in VMware ESXi OpenSLP service (potentially enabling remote code execution).
The version that knows your environment.
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.