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Vulnerability record · CVE-2020-26082 · published 4 August 2023

CVE-2020-26082: Cisco asyncos improper input validation vulnerability

Cisco · Asyncos

A vulnerability in the zip decompression engine of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass content filters that are configured on an affected device. The vulnerability is due to improper handling of password-protected zip files. An attacker could exploit this vulnerability by sending a malicious file inside a crafted zip-compressed file to an affected device. A successful exploit could allow the attacker to bypass configured content filters that would normally drop the email.

5.3 CVSS 3.1 Medium EPSS 0.63% · top 51.4% CWE-20 · Improper input validation
5.3CVSS 3.1 base score
0.63%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 the zip decompression engine of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass content filters that are configured on an affected device. The vulnerability is due to improper handling of password-protected zip files. An attacker could exploit this vulnerability by sending a malicious file inside a crafted zip-compressed file to an affected device. A successful exploit could allow the attacker to bypass configured content filters that would normally drop the email.

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

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-zip-bypass-gbU4gtTg Vendor Advisory
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-zip-bypass-gbU4gtTg Vendor Advisory

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Related vulnerabilities

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

10.0CVE-2025-20393Cisco AsyncOS Spam Quarantine HTTP request validation flaw allows root command executionCisco AsyncOS Software for Secure Email Gateway and Secure Email and Web Manager fails to properly validate HTTP requests in the Spam Quarantine feat…KEVEPSS 32%analysed9.8CVE-2026-76461Cisco AsyncOS email parsing SQL injection allows root command executionCisco AsyncOS Software for Cisco Secure Email Gateway fails to properly validate email parsing input, allowing crafted email messages containing mali…KEVEPSS 28%analysed8.8CVE-2022-20871Cisco asyncos os command injection vulnerabilityA vulnerability in the web management interface of Cisco AsyncOS for Cisco Secure Web Appliance, formerly Cisco Web Security Appliance…EPSS 1.9%8.8CVE-2022-20868Cisco asyncos hard-coded credentials vulnerabilityA vulnerability in the web-based management interface of Cisco Email Security Appliance, Cisco Secure Email and Web Manager and Cisco Secure Web Appl…EPSS 0.76%8.8CVE-2021-1359Cisco web security appliance vulnerabilityA vulnerability in the configuration management of Cisco AsyncOS for Cisco Web Security Appliance (WSA) could allow an authenticated, remote attacker…EPSS 1.9%8.8CVE-2019-15956Cisco asyncos improper access control vulnerabilityA vulnerability in the web management interface of Cisco AsyncOS Software for Cisco Web Security Appliance (WSA) could allow an authenticated, remote…EPSS 0.98%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%8.6CVE-2019-1886Cisco asyncos improper input validation vulnerabilityA vulnerability in the HTTPS decryption feature of Cisco Web Security Appliance (WSA) could allow an unauthenticated, remote attacker to cause a deni…EPSS 1.3%

Source: NIST National Vulnerability Database (record CVE-2020-26082), CISA KEV, FIRST EPSS (scores of 2026-10-10). This page is refreshed as NVD updates the record.