CVE-2025-20393
About
A vulnerability in the Spam Quarantine feature of Cisco AsyncOS Software for Cisco Secure Email Gateway and Cisco Secure Email and Web Manager could allow an unauthenticated, remote attacker to execute arbitrary system commands on an affected device with root privileges.
This vulnerability is due to insufficient validation of HTTP requests by the Spam Quarantine feature. An attacker could exploit this vulnerability by sending a crafted HTTP request to the affected device. A successful exploit could allow the attacker to execute arbitrary commands on the underlying operating system with root privileges.
Rainforest analyst review
The Spam Quarantine feature in Cisco AsyncOS for the Secure Email Gateway and Secure Email and Web Manager fails to validate incoming HTTP requests adequately. An unauthenticated attacker sends a crafted request to that feature and, because input is passed through to the underlying operating system without sufficient checks, executes arbitrary commands as root. No credentials and no user interaction are required — a single request to the quarantine interface yields full control of the appliance.
These are security appliances that sit inline for an organization's email, filtering and quarantining messages, so they see the full mail stream and are trusted by the surrounding infrastructure; root on one is both a deep foothold and a window into sensitive communications. The fact that a defensive control becomes the entry point makes this especially costly, since these devices are often reachable to accept and manage mail. Apply Cisco's fixed AsyncOS release, and restrict access to the quarantine and management interfaces to trusted administrative networks rather than leaving them broadly reachable. Given root-level impact with no authentication, review affected appliances for unexpected processes and configuration changes.
References
Related CVEs
Frequently asked questions
What is CVE-2025-20393?
A vulnerability in the Spam Quarantine feature of Cisco AsyncOS Software for Cisco Secure Email Gateway and Cisco Secure Email and Web Manager could allow an unauthenticated, remote attacker to execute arbitrary system commands on an affected device with root privileges. This vulnerability is due to insufficient validation of HTTP requests by the Spam Quarantine feature.
How severe is CVE-2025-20393?
CVE-2025-20393 carries a CVSS 3.1 base score of 10, rated critical. On the Rainforest Risk Index — which weighs the severity alongside how easy the flaw is to reach and how broad its impact is — it scores 100 out of 100, in the critical band.
How is CVE-2025-20393 exploited?
According to the CVSS vector (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H): attack vector Network, attack complexity Low, privileges required None, user interaction None. Impact on confidentiality High, integrity High and availability High.
Which products are affected by CVE-2025-20393?
Public advisories list the following as affected: asyncos, secure email and web manager m170, secure email and web manager m190, secure email and web manager m195, secure email and web manager m380, secure email and web manager m390, +15. Check the references on this page for the exact versions each vendor confirms.
How do I fix CVE-2025-20393?
Apply the fix the vendor published — the references on this page link to the primary advisories and patches. When patching can't happen right away, reduce the exposure of the affected component and watch it for exploitation attempts. Rainforest customers see this vulnerability correlated to their own assets and prioritized by real exposure, not by score alone.
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