# CVE-2020-29390: Zeroshell - RCE

> Live exploitation tracking for CVE-2020-29390 by the CrowdSec Live Exploit Tracker, built from real-world attack data crowdsourced from CrowdSec's global network.

Page: https://tracker.crowdsec.net/cves/CVE-2020-29390

## Key facts

- **Exploitation phase:** Limited Exploitation. The vulnerability is known but shows very limited attacker interest or exploitation activity.
- **CVSS score:** 9.8
- **Public exploit available:** Yes
- **Affected products:** Zeroshell
- **Weaknesses:** CWE-78 (Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'))
- **Tags:** web_application

## Description

Zeroshell 3.9.3 contains a command injection vulnerability in the /cgi-bin/kerbynet StartSessionSubmit parameter that could allow an unauthenticated attacker to execute a system command by using shell metacharacters and the %0a character.

## CrowdSec analysis

[CVE-2020-29390](https://euvd.enisa.europa.eu/vulnerability/CVE-2020-29390) is a critical vulnerability in Zeroshell that enables unauthenticated remote code execution via command injection within the CGI interface.

CrowdSec has been tracking this vulnerability and its exploits since 26th of May 2025.

Data from the CrowdSec community indicates that exploitation of CVE-2020-29390 is highly selective and intelligence-driven. Threat actors use advanced reconnaissance and carefully choose their targets, often as part of sophisticated campaigns or advanced persistent threat operations.
Data from the CrowdSec community also indicates a gradual decrease in attacks targeting CVE-2020-29390. While still present in the wild, exploitation levels have dropped noticeably week-over-week. This may signal that the vulnerability is becoming less relevant or that defenses are improving fast enough for attackers to lose interest.

Observed exploitation activity typically targets URLs containing `/cgi-bin/kerbynet`.

## Timeline

- 2020-11-30: CVE Published. CVE-2020-29390 is published to NVD.
- 2025-05-26: Rule Released. CrowdSec releases a rule to detect CVE-2020-29390 exploitation attempts against the CrowdSec Network.
- 2025-05-28: CrowdSec First Seen. CrowdSec observes in-the-wild exploitation of CVE-2020-29390 for the first time.

## References

- https://rustlang.rs/posts/zeroshell_linux_router_rce/

## Live exploitation data

The [Live Exploit Tracker page](https://tracker.crowdsec.net/cves/CVE-2020-29390) follows observed exploitation activity for CVE-2020-29390. [Request an API key](https://tracker.crowdsec.net/request-api-key) for full access to its exploitation timeline, attacking IP addresses and blocklists.