Cisco Secure Email Gateway: attackers can read or change files
OFFICIAL NAME: Cisco Secure Email Gateway Relative Path Traversal Vulnerability
WHAT IT IS · EMAILIt carries internal and customer mail.
DO THIS FIRSTPatch it, or ask your email provider whether they have. Not sure if you use it? Send this page to your IT provider or security lead and ask.
TECHNICAL SUMMARY 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.
WHY THIS VERDICT Attacks are confirmed. The vulnerability is 27 days old, so many systems are likely still unpatched. Ready-made attack tools are public. It affects a product that faces the internet or gives remote access. The severity score is critical (9.8).
WHY IT RANKS HERE Exploitation is confirmed by an authoritative source. The product faces the internet or gives remote access. Ready-made attack tools are public.
- HIGHEST CONFIRMED RUNG
- EXPLOITED
- CISA KEV
- LISTED
- EXPLOIT CODE
- READY TO USE
How far has it climbed?
01 TALK
■ CONFIRMEDNEWEST EVIDENCE · 2 INDEPENDENT SOURCESCVE-2026-76519 discussed publicly (CIRCL sighting). CVE-2026-76519 discussed publicly (CIRCL sighting).
02 EXPOSED
□ NOT TRACKED YETNO SOURCE FOR THIS STEP YETWe have no source that counts exposed systems yet. Internet scan data needs a partnership we do not have. No evidence here does not mean nothing is exposed.
03 TRIED
■ CONFIRMEDNEWEST EVIDENCE · 2 INDEPENDENT SOURCESAttacks that worked are confirmed (step 4), so attempts count as confirmed too.
04 EXPLOITED
■ CONFIRMEDNEWEST EVIDENCE · 2 INDEPENDENT SOURCESCISA Vulnrichment marks CVE-2026-76519 as actively exploited. 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.
05 DAMAGE
□ NOT TRACKED YETNO SOURCE FOR THIS STEP YETBreach notices and filings rarely name the flaw that was used, so we cannot link them to this event yet. No evidence here does not mean no harm.
When each thing happened
- DISCLOSED
- EXPLOIT CODE PUBLICDATE UNKNOWN
- FIRST ATTACK REPORT
- CISA KEV LISTING
- US FEDERAL DEADLINE
THE FIX
CISA's instruction: apply the vendor's fix, or stop using the product if no fix exists. The deadline CISA set for US federal agencies, Oct 17, 2026, has passed. It is a US government deadline; use it as a guide.
Questions to ask this week
- Do we run Cisco Secure Email Gateway? If yes, is it patched or cut off from the internet?
- Who owns fixing it, and by what date?
- Have we checked for signs of attack since the first report, not just since the patch?
How it unfolded
- Attack activity. OCT 13, 2026Cisco Secure Email Gateway Relative Path Traversal Vulnerability
- OCT 13, 2026Metasploit exploit module: Cisco Secure Email Gateway AMP Arbitrary File Write RCE
- Attack activity. OCT 14, 2026CISA Vulnrichment marks CVE-2026-76519 as actively exploited
- OCT 14, 2026Cisco security advisory (AV26-1042) – Update 1
- OCT 14, 20261 public GitHub repository claims a proof of concept for CVE-2026-76519
- OCT 28, 2026CVE-2026-76519 discussed publicly (CIRCL sighting) (2 reports, latest NOV 7)
SOURCES
- [1] CIRCL Vulnerability-Lookup sightings: CVE-2026-76519 discussed publicly (CIRCL sighting), NOV 7
- [2] PoC-in-GitHub: 1 public GitHub repository claims a proof of concept for CVE-2026-76519, OCT 14
- [3] Canadian Centre for Cyber Security: Cisco security advisory (AV26-1042) – Update 1, OCT 14
- [4] CVE List V5 and CISA Vulnrichment: CISA Vulnrichment marks CVE-2026-76519 as actively exploited, OCT 14
- [5] CISA Known Exploited Vulnerabilities: Cisco Secure Email Gateway Relative Path Traversal Vulnerability, OCT 13
- [6] Metasploit module metadata: Metasploit exploit module: Cisco Secure Email Gateway AMP Arbitrary File Write RCE, OCT 13
- [7] CIRCL Vulnerability-Lookup sightings: 1 more reports