Zero-day vulnerability in Email Security Gateway

OS command injection
CVE-2025-59689

Vulnerability details

Advisory: SB2025092429 - Remote code execution in Libraesva Email Security Gateway (ESG)

Vulnerable component: Email Security Gateway

CVE-ID: CVE-2025-59689

CVSSv3 score: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C

CWE-ID: CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

Description:

The vulnerability allows a remote attacker to execute arbitrary shell commands on the target system.

The vulnerability exists due to improper input validation when handling archives in email attachments. A remote attacker can send a specially crafted email to the affected system and execute arbitrary OS commands.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Note, the vulnerability is being actively exploited in the wild. 

External links:

https://docs.libraesva.com/knowledgebase/security-advisory-command-injection-vulnerability-cve-2025-59689/

About zero-day vulnerabilities

Zero-day vulnerability is an undisclosed vulnerability in software that hackers can exploit to compromise computer programs, gain unauthorized access to sensitive data, penetrate networks, etc. We consider vulnerability a zero-day when there is no solution provided from software vendor and the vulnerability is being actively exploited by malicious actors.

Zero-day candidate is a potential zero-day vulnerability in software which might have been used in targeted attacks, however there is no evidence to support this suggestion.