CVE-2022-20653 Cisco Email Security Appliance DNS Verification Denial of Service Vulnerability
Remote attackers can cause denial of service on Cisco Email Security Appliances by sending specially formatted emails that trigger insufficient error handling in DNS verification.
- 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-2022-20653?
CVE-2022-20653 is a high-severity denial of service vulnerability in Cisco Asyncos, published on 17 Feb 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability in the DNS-based Authentication of Named Entities (DANE) email verification component of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient error handling in DNS name resolution by the affected software. An attacker could exploit this vulnerability by sending specially formatted email messages that are processed by an affected device. A successful exploit could allow the attacker to cause the device to become unreachable from management interfaces or to process additional email messages for a period of time until the device recovers, resulting in a DoS condition. Continued attacks could cause the device to become completely unavailable, resulting in a persistent DoS condition.
Weakness: CWE-399
Which versions are affected by CVE-2022-20653?
It affects 1 product.
Products include Cisco Asyncos.
How do I fix CVE-2022-20653?
No fix has been published for CVE-2022-20653 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-2022-20653 being exploited?
There is no known exploitation of CVE-2022-20653 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-p3pv-g3c9-4qf8.