Cisco Secure Email Gateway Relative Path Traversal
CVE-2026-76519 is a critical-severity relative path traversal vulnerability in Cisco Secure Email from Cisco, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Cisco Secure Email versions: 14.0.0-698; 13.5.1-277; 13.0.0-392, and others listed below. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on October 14, 2026, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Asyncos to 15.5.5-014 or 16.5.0-780, whichever matches your release line, or a later version.
- CISA's required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
- Read the advisory on sec.cloudapps.cisco.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cisco | Cisco Secure Email | 14.0.0-698; 13.5.1-277; 13.0.0-392; 14.2.0-620; 13.0.5-007; 13.5.4-038; 14.2.1-020; 14.3.0-032; and 15 more ranges | Not stated |
| Cisco | Asyncos | 15.0 up to, but not including, 15.5.5-014; 16.0 up to, but not including, 16.5.0-780 | 15.5.5-014, 16.5.0-780 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (cisco.com).
Official description
A vulnerability in the Advanced Malware Protection (AMP) feature of Cisco Secure Email Gateway could allow an unauthenticated, remote attacker to write arbitrary files on the underlying operating system. This vulnerability is due to improper handling of email attachments when the file reputation service is enabled. An attacker could exploit this vulnerability by sending an email that contains a crafted attachment through an affected device. A successful exploit could allow the attacker to write arbitrary files and execute commands with root privileges on the underlying operating system.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Relative Path Traversal
The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize sequences such as.. that can resolve to a location that is outside of that directory.
How developers prevent this class of flaw
- Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Record last changed materially (score, affected products, status or references).
- Deadline for US federal agencies to remediate, set by CISA.
References
Advisories
Third-party and government advisories
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-76519US Government Resource
Our coverage
Other vulnerabilities in Cisco Secure Email
- 9.8 Critical severity
Cisco Secure Email Gateway SQL Injection Exploited
- 9.8 Critical severity
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 10.0 Critical severity
Recent Relative Path Traversal vulnerabilities
- 7.5 High severity
- 8.8 High severity
- 9.4 Critical severity
- 9.1 Critical severity
- 7.3 High severity
- 8.5 High severity
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