Cisco Email Security Appliance URL Filtering Bypass Vulnerability

Published 8 y ago 2018-10-05 · modified 4 mo ago 2026-06-17 · JSON

CVSS

5.3

v3.0 · NVD

CISA KEV

not known exploited

EPSS

2.3%

percentile 83%

Public exploits

none known

A vulnerability in the anti-spam protection mechanisms of Cisco AsyncOS Software for the Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass certain content filters on an affected device. The vulnerability is due to incomplete input and validation checking mechanisms for certain Sender Policy Framework (SPF) messages that are sent to an affected device. An attacker could exploit this vulnerability by sending a customized SPF packet to an affected device. If successful, an exploit could allow the attacker to bypass the URL filters that are configured for the affected device, which could allow malicious URLs to pass through the device.

CISA SSVC assessment

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 23 mo ago 2024-11-25

Exploit prediction (EPSS)

2.28% probability of exploitation in the next 30 days, higher than 83% of all scored CVEs.

CVSS scores

Assigned by	Version	Score	Vector
NVD	3.0	5.3	`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`
NVD	2.0	5.0	`AV:N/AC:L/Au:N/C:N/I:P/A:N`

Affected products

Cisco Cisco Email Security Appliance (ESA)

Classification

Weakness

CWE-284 Improper Access Control
CWE-20 Improper Input Validation

References

securityfocus.com /bid/105300 · vdb-entry, x_refsource_BID, x_transferred
securitytracker.com /id/1041687 · vdb-entry, x_refsource_SECTRACK, x_transferred
tools.cisco.com /security/center/content/CiscoSecurityAdvisory/cisco-sa-20180905-esa-url-bypass · vendor-advisory, x_refsource_CISCO, x_transferred

Sources

CVE List: CVE-2018-0447
NVD: CVE-2018-0447

vulnwire keeps one entry per vulnerability: the CVE id wins, then GHSA; records that alias each other are merged. Machine-readable: JSON.

Summary