CVE-2019-1983 Cisco Email Security Appliance and Cisco Content Security Management Appliance Denial of Service Vulnerability
Unauthenticated remote attackers can cause repeated process crashes and service unavailability on Cisco ESA and SMA devices by sending emails with crafted attachments.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2019-1983?
CVE-2019-1983 is a high-severity denial of service vulnerability in Cisco Asyncos, published on 23 Sep 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability in the email message filtering feature of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) and Cisco Content Security Management Appliance (SMA) could allow an unauthenticated, remote attacker to cause repeated crashes in some internal processes that are running on the affected devices, resulting in a denial of service (DoS) condition. The vulnerability is due to insufficient input validation of email attachments. An attacker could exploit this vulnerability by sending an email message with a crafted attachment through an affected device. A successful exploit could allow the attacker to cause specific processes to crash repeatedly, resulting in the complete unavailability of both the Cisco Advanced Malware Protection (AMP) and message tracking features and in severe performance degradation while processing email. After the affected processes restart, the software resumes filtering for the same attachment, causing the affected processes to crash and restart again. A successful exploit could also allow the attacker to cause a repeated DoS condition. Manual intervention may be required to recover from this situation.
Weakness: CWE-20
Which versions are affected by CVE-2019-1983?
It affects 3 products.
Products include Cisco Asyncos, Cisco Content Security Management Appliance, Cisco Email Security Appliance.
How do I fix CVE-2019-1983?
No fix has been published for CVE-2019-1983 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2019-1983 being exploited?
There is no known exploitation of CVE-2019-1983 in the wild and no public exploit code.
Other vulnerabilities in Cisco Asyncos
- CVE-2025-20393 Cisco Multiple Products Improper Input Validation
- CVE-2026-76519 Cisco Secure Email Gateway Relative Path Traversal
- CVE-2026-76461 Cisco Secure Email Gateway SQL Injection
- CVE-2024-20435 Command injection in Cisco Secure Web Appliance
- CVE-2019-15956 Cisco Web Security Appliance Unauthorized Device Reset Vulnerability
Sources
Also known as GHSA-v6r4-c6r4-r649.