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Vulnerability record · CVE-2015-6291 · published 6 November 2015

CVE-2015-6291: Cisco email security appliance improper input validation vulnerability

Cisco · Email Security Appliance

Cisco 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 malformed fields during body-contains, attachment-contains, every-attachment-contains, attachment-binary-contains, dictionary-match, and attachment-dictionary-match filtering, which allows remote attackers to cause a denial of service (memory consumption) via a crafted attachment in an e-mail message, aka Bug ID CSCuv47151.

7.8 CVSS 2.0 High EPSS 1.9% · top 20.9% CWE-20 · Improper input validation
7.8CVSS 2.0 base score
1.9%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

Description

Cisco 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 malformed fields during body-contains, attachment-contains, every-attachment-contains, attachment-binary-contains, dictionary-match, and attachment-dictionary-match filtering, which allows remote attackers to cause a denial of service (memory consumption) via a crafted attachment in an e-mail message, aka Bug ID CSCuv47151.

AV:N/AC:L/Au:N/C:N/I:N/A:C

Affected products

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

References

LinkTags
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20151104-esa2 Vendor Advisory
http://www.securitytracker.com/id/1034064
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20151104-esa2 Vendor Advisory
http://www.securitytracker.com/id/1034064

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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%7.7CVE-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-2022-20960Cisco email security appliance uncontrolled resource consumption vulnerabilityA vulnerability in Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated remote attacker to cause a denial o…EPSS 0.83%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-2015-6291), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.