Our automated tracking framework flagged that CISA added CVE-2026-76519 (Cisco Secure Email Gateway) to the Known Exploited Vulnerabilities (KEV) catalog on October 15, 2026. A KEV listing is CISA’s official confirmation that the flaw is being exploited in the wild — U.S. federal agencies must patch it by a fixed deadline. Here is what our data shows.
What CISA Reported
CISA describes the flaw as follows: “Cisco Secure Email Gateway contains a relative path traversal vulnerability that could allow an unauthenticated, remote attacker to write arbitrary files on the underlying operating system.”
Under Binding Operational Directive rules, U.S. federal agencies must remediate CVE-2026-76519 by October 17, 2026 — a 3-day window. Private organizations are not bound by the deadline, but CISA treats it as the benchmark for how urgently a confirmed-exploited flaw should be patched.
The Details
| CVE | CVE-2026-76519 |
| Vendor / product | Cisco Secure Email Gateway |
| Vulnerability | Cisco Secure Email Gateway Relative Path Traversal Vulnerability |
| CVSS base score | 9.8 |
| Added to KEV | October 14, 2026 |
| Days public before listing (NVD → KEV lag) | 0 |
| Federal patch deadline | October 17, 2026 |
| Known ransomware use | No |
How This Compares to Cisco’s Track Record
This one was listed on or before its public disclosure (a lag of 0 days) — a zero-day exploited at or before the vulnerability was even published. Cisco currently ranks #12 on our KEV Lag leaderboard.
| Cisco in the CISA KEV catalog | Value |
|---|---|
| Tracked KEV entries | 101 |
| Median lag (public → KEV listing) | 1014 days |
| 0-day rate (exploited at or before disclosure) | 18% |
| Entries tied to known ransomware campaigns | 6 |
For perspective, the median across all 1745 tracked KEV entries is 245 days — Cisco’s exploited vulnerabilities are flagged slower than the catalog average.
Other Recent Cisco KEV Additions
The most recent Cisco vulnerabilities CISA has confirmed as actively exploited, from our tracker:
| CVE | Product | Added to KEV | Lag (days) | Ransomware |
|---|---|---|---|---|
| CVE-2026-76504 | Catalyst SD-WAN Manager | September 30, 2026 | 0 | No |
| CVE-2026-76460 | Identity Services Engine | September 16, 2026 | 0 | No |
| CVE-2026-76461 | Secure Email Gateway | September 14, 2026 | 0 | No |
| CVE-2026-20079 | Secure Firewall Management Center (FMC) and Security Cloud Control (SCC) Firewall Management | September 9, 2026 | 189 | No |
| CVE-2026-20349 | Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) | August 11, 2026 | 0 | No |
Defense guide: How to Detect Zero-day Vulnerability: Attack Chain & Defense — detection signals, attack chain and response steps for this class of attack.
What This Means for Defenders
CISA has added CVE-2026-76519, a Relative Path Traversal Vulnerability in Cisco Secure Email Gateway, to its Known Exploited Vulnerabilities (KEV) catalog. It has a critical CVSS base score of 9.8. This vulnerability was listed in the KEV catalog on 2026-10-14, with zero days public before the KEV listing. This 0-day lag means there was no detection window between public disclosure and confirmed exploitation.
All organizations using Cisco Secure Email Gateway should patch this vulnerability immediately. The federal patch deadline is 2026-10-17. While ransomware use hasn’t been confirmed for this CVE, its critical severity and confirmed exploitation make it a high-priority target for various attack scenarios.
If you can’t apply the patch before the deadline, restrict access to affected systems. Enhance network segmentation, strengthen perimeter defenses, and monitor network traffic for unusual activity originating from or destined for Cisco Secure Email Gateway instances. Review access controls and consider temporary restrictions on sensitive functions accessed via these gateways until patching is complete.
Related Coverage
- Cisco’s CVE-2026-20316 Was Exploited in 0 Days — Well Under Its 1245-Day Median (July 2026)
- Cisco’s CVE-2026-20349 Was Exploited in 0 Days — Well Under Its 1245-Day Median (August 2026)
How We Track This
This report was generated from our CISA KEV Lag Tracker, which syncs the official CISA KEV catalog daily and records the date each CVE is added. For every entry we retrieve the original NVD publication date and compute the lag in calendar days. No dates or figures on this page are estimated or taken from third-party sources — they come directly from CISA and NVD records.
