How severe is CVE-2016-6458?

CVE-2016-6458 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2016-6458 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (80th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-6458?

CVE-2016-6458 primarily affects Cisco Email Security Appliance Firmware. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-6458?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2016-6458 published?

CVE-2016-6458 was published on 2016-11-19 and last updated on 2026-06-17.

CVE-2016-6458

CVE-2016-6458 is a high-severity vulnerability in Cisco Email Security Appliance Firmware with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (80th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Cisco Email Security Appliance Firmware
Published: 2016-11-19
Last modified: 2026-06-17

Description

A vulnerability in the content filtering functionality of Cisco AsyncOS Software for Cisco Email Security Appliances could allow an unauthenticated, remote attacker to bypass content filters configured on an affected device. Email that should have been filtered could instead be forwarded by the device. This vulnerability affects all releases prior to the first fixed release of Cisco AsyncOS Software for Cisco Email Security Appliances, both virtual and hardware appliances, if the software is configured to use a content filter for email attachments that are protected or encrypted. More Information: CSCva52546. Known Affected Releases: 10.0.0-125 9.7.1-066.

Frequently asked questions

What is CVE-2016-6458?: A vulnerability in the content filtering functionality of Cisco AsyncOS Software for Cisco Email Security Appliances could allow an unauthenticated, remote attacker to bypass content filters configured on an affected device. Email that should have been filtered could instead be forwarded by the device. This vulnerability affects all releases prior to the first fixed release of Cisco AsyncOS Software for Cisco Email Security Appliances, both virtual and hardware appliances, if the software is configured to use a content filter for email attachments that are protected or encrypted. More Information: CSCva52546. Known Affected Releases: 10.0.0-125 9.7.1-066.
How severe is CVE-2016-6458?: CVE-2016-6458 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2016-6458 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (80th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-6458?: CVE-2016-6458 primarily affects Cisco Email Security Appliance Firmware. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-6458?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2016-6458 published?: CVE-2016-6458 was published on 2016-11-19 and last updated on 2026-06-17.

References

Affected products (8)

cpe:2.3:o:cisco:email_security_appliance_firmware:9.7.1-066:*:*:*:*:*:*:*
cpe:2.3:o:cisco:email_security_appliance_firmware:9.7.2-046:*:*:*:*:*:*:*
cpe:2.3:o:cisco:email_security_appliance_firmware:9.7.2-047:*:*:*:*:*:*:*
cpe:2.3:o:cisco:email_security_appliance_firmware:9.7.2-054:*:*:*:*:*:*:*
cpe:2.3:o:cisco:email_security_appliance_firmware:9.9.6-026:*:*:*:*:*:*:*
cpe:2.3:o:cisco:email_security_appliance_firmware:9.9_base:*:*:*:*:*:*:*
cpe:2.3:o:cisco:email_security_appliance_firmware:10.0.0-124:*:*:*:*:*:*:*
cpe:2.3:o:cisco:email_security_appliance_firmware:10.0.0-125:*:*:*:*:*:*:*

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