Cisco patches actively exploited email gateway zero-day (CVE-2026-76461)
Actively exploited zero-day SQL injection (CVE-2026-76461) in Cisco Secure Email Gateway allows unauthenticated root command execution; CISA ordered federal remediation by September 17.
Cisco confirmed attackers are exploiting zero-day CVE-2026-76461, an unauthenticated SQL injection in the email parsing logic of AsyncOS on Secure Email Gateway appliances (versions 16.5, 16.0, 15.5 and earlier) and Secure Email Cloud. Successful exploitation yields arbitrary SQL execution and root-level command execution on the underlying OS without user interaction. Cisco became aware of active exploitation in September 2025, has directly contacted affected cloud customers, and released fixed releases 15.5.5-014, 16.0.4-302, and 16.5.0-780. CISA added the flaw to its Known Exploited Vulnerabilities catalog and required federal civilian agencies to patch by September 17 and hunt for compromise.
- Unauthenticated SQL injection via crafted email gives attackers root command execution on affected appliances.
- Affects AsyncOS 15.5/16.0/16.5 and earlier on physical, virtual, and cloud Secure Email Gateways.
- CISA added CVE-2026-76461 to KEV with a September 17 federal remediation deadline.
- Fix releases 15.5.5-014 and 16.5.0-780 also patch several additional critical vulnerabilities.
- Root-level attackers may purge logs and hide indicators, so external network and firewall logs should be reviewed.
Vulnerabilities mentioned
All| CVE | Vulnerability | CVSS | EPSS | Signals | Published |
|---|---|---|---|---|---|
| CVE-2025-20393 | Improper Input Validation in Cisco Secure Email and Web Appliances Allows Root Commands | 10.0 | 32% | KEV | KEV |
| CVE-2026-76461 | Unauthenticated SQL Injection to Root RCE in Cisco Secure Email Gateway | 9.8 | 30% | KEVPoC ×3 | KEV |
From the original article
2 min read at helpnetsecurity.com
Attackers have leveraged a zero-day SQL injection vulnerability (CVE-2026-76461) to compromise Cisco Secure Email Gateway appliances, Cisco confirmed on Monday. The vendor’s Product Security Incident Response Team became aware of active exploitation of this vulnerability in September 2025, and has shared indicators of compromise that organizations can look for to check whether they’ve been hit.
By Zeljka Zorz · helpnetsecurity.com
A short excerpt; the article and its images belong to the publisher. Summary, key facts and assessment above are AI-written from the article and can be wrong.