CVE-2016-6372

CVE-2016-6372 is a high-severity vulnerability in Cisco Email Security Appliance 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

Description

A vulnerability in the email message and content filtering for malformed Multipurpose Internet Mail Extensions (MIME) headers of Cisco AsyncOS Software for Cisco Email Security Appliances (ESA) and Web Security Appliances (WSA) could allow an unauthenticated, remote attacker to bypass the filtering functionality of the targeted device. Emails that should have been quarantined could instead be processed. Affected Products: This vulnerability affects all releases prior to the first fixed release of Cisco AsyncOS Software for Cisco ESA and Cisco WSA on both virtual and hardware appliances that are configured with message or content filters to scan incoming email attachments. More Information: CSCuy54740, CSCuy75174. Known Affected Releases: 9.7.1-066 9.5.0-575 WSA10.0.0-000. Known Fixed Releases: 10.0.0-125 9.1.1-038 9.7.2-047.

Frequently asked questions

What is CVE-2016-6372?
A vulnerability in the email message and content filtering for malformed Multipurpose Internet Mail Extensions (MIME) headers of Cisco AsyncOS Software for Cisco Email Security Appliances (ESA) and Web Security Appliances (WSA) could allow an unauthenticated, remote attacker to bypass the filtering functionality of the targeted device. Emails that should have been quarantined could instead be processed. Affected Products: This vulnerability affects all releases prior to the first fixed release of Cisco AsyncOS Software for Cisco ESA and Cisco WSA on both virtual and hardware appliances that are configured with message or content filters to scan incoming email attachments. More Information: CSCuy54740, CSCuy75174. Known Affected Releases: 9.7.1-066 9.5.0-575 WSA10.0.0-000. Known Fixed Releases: 10.0.0-125 9.1.1-038 9.7.2-047.
How severe is CVE-2016-6372?
CVE-2016-6372 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 high, integrity none, and availability none.
Is CVE-2016-6372 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-6372?
CVE-2016-6372 primarily affects Cisco Email Security Appliance. In total, 77 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-6372?
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-2016-6372 published?
CVE-2016-6372 was published on 2016-10-28 and last updated on 2026-06-17.

References

Affected products (77)

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