CVE-2021-34741

Cisco Email Security Appliance Denial of Service Vulnerability

Description

A vulnerability in the email scanning algorithm of Cisco AsyncOS software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to perform a denial of service (DoS) attack against an affected device. This vulnerability is due to insufficient input validation of incoming emails. An attacker could exploit this vulnerability by sending a crafted email through Cisco ESA. A successful exploit could allow the attacker to exhaust all the available CPU resources on an affected device for an extended period of time, preventing other emails from being processed and resulting in a DoS condition.

Category

7.5
CVSS
Severity: High
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.24%
Vendor Advisory cisco.com
Affected: Cisco Cisco Email Security Appliance (ESA)
Published at:
Updated at:

References

Frequently Asked Questions

What is the severity of CVE-2021-34741?
CVE-2021-34741 has been scored as a high severity vulnerability.
How to fix CVE-2021-34741?
To fix CVE-2021-34741, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-34741 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2021-34741 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-34741?
CVE-2021-34741 affects Cisco Cisco Email Security Appliance (ESA).
This platform uses data from the NIST NVD, MITRE CVE, MITRE CWE, First.org and CISA KEV but is not endorsed or certified by these entities. CVE is a registred trademark of the MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. CWE is a registred trademark of the MITRE Corporation and the authoritative source of CWE content is MITRE's CWE web site.
© 2025 Under My Watch. All Rights Reserved.