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.

Scores

EPSS (exploitation in 30 days)

1.3% · top 30% of all CVEs (6 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: yes · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.

Weakness

• CWE-770 (opens in a new tab)All about CWE-770 and its CVEs

Affected products

• Cisco · Cisco Email Security Appliance (ESA)

  • affected n/a

What to do

Exploitation: The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

References (1)

• 20211103 Cisco Email Security Appliance Denial of Service Vulnerability (opens in a new tab)vendor-advisoryx_refsource_CISCOx_transferred

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2021-34741](https://trackcve.app/badge/CVE-2021-34741.svg)](https://trackcve.app/cve/CVE-2021-34741)

Record last updated 7 Nov 2024, 21:44 UTC.