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Vulnerability record · CVE-2022-20960 · published 4 November 2022

CVE-2022-20960: Cisco email security appliance uncontrolled resource consumption vulnerability

Cisco · Email Security Appliance

A vulnerability in 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 improper handling of certain TLS connections that are processed by an affected device. An attacker could exploit this vulnerability by establishing a large number of concurrent TLS connections to an affected device. A successful exploit could allow the attacker to cause the device to drop new TLS email messages that come from the associated email servers. Exploitation of this vulnerability does not cause the affected device to unexpectedly reload. The device will recover autonomously within a few hours of when the attack is halted or mitigated.

7.5 CVSS 3.1 High EPSS 0.83% · top 44.1% CWE-400 · Uncontrolled resource consumptionCWE-295 · Improper certificate validation
7.5CVSS 3.1 base score
0.83%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

A vulnerability in 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 improper handling of certain TLS connections that are processed by an affected device. An attacker could exploit this vulnerability by establishing a large number of concurrent TLS connections to an affected device. A successful exploit could allow the attacker to cause the device to drop new TLS email messages that come from the associated email servers. Exploitation of this vulnerability does not cause the affected device to unexpectedly reload. The device will recover autonomously within a few hours of when the attack is halted or mitigated.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-dos-gdghHmbV
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-dos-gdghHmbV

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2022-20798Cisco email security appliance improper authentication vulnerabilityA vulnerability in the external authentication functionality of Cisco Secure Email and Web Manager, formerly known as Cisco Security Management Appli…EPSS 1.5%8.6CVE-2019-1947Cisco email security appliance improper input validation vulnerabilityA vulnerability in the email message filtering feature of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthentica…EPSS 1.9%7.8CVE-2015-6321Cisco web security appliance vulnerabilityCisco AsyncOS before 8.5.7-042, 9.x before 9.1.0-032, 9.1.x before 9.1.1-023, and 9.5.x and 9.6.x before 9.6.0-042 on Email Security Appliance (ESA) …EPSS 2.8%7.8CVE-2015-6291Cisco email security appliance improper input validation vulnerabilityCisco AsyncOS before 8.5.7-043, 9.x before 9.1.1-023, and 9.5.x and 9.6.x before 9.6.0-046 on Email Security Appliance (ESA) devices mishandles malfo…EPSS 1.9%7.7CVE-2022-20664Cisco email security appliance information exposure vulnerabilityA vulnerability in the web management interface of Cisco Secure Email and Web Manager, formerly Cisco Security Management Appliance (SMA), and Cisco …EPSS 1.0%7.5CVE-2020-3548Cisco email security appliance vulnerabilityA vulnerability in the Transport Layer Security (TLS) protocol implementation of Cisco AsyncOS software for Cisco Email Security Appliance …EPSS 0.84%7.5CVE-2020-3133Cisco email security appliance improper input validation vulnerabilityA vulnerability in the email message scanning of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remo…EPSS 1.4%7.5CVE-2019-1921Cisco email security appliance improper input validation vulnerabilityA vulnerability in the attachment scanning of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote …EPSS 1.4%

Source: NIST National Vulnerability Database (record CVE-2022-20960), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.