Zeroshell - RCE (CVE-2020-29390)
311Exploiting IPs reported
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 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.
CrowdSec network observations suggest that most exploitation of CVE-2020-29390 involves focused reconnaissance to identify viable targets. Attackers typically tailor their campaigns based on system exposure and configuration. It is unlikely that a given attack is accidental. CrowdSec data also reveals a clear uptick in attacks involving CVE-2020-29390 over the past week. Activity is above the usual baseline, suggesting growing attention from attackers. This may reflect rising awareness, recent exploit releases, or expanded targeting efforts.
Observed exploitation activity typically targets URLs containing /cgi-bin/kerbynet.
Exploitation
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Common Weakness Enumeration (CWE)
Protection
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Blocklist
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