How severe is CVE-2016-6407?

CVE-2016-6407 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 none, and availability high.

Is CVE-2016-6407 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-6407?

CVE-2016-6407 primarily affects Cisco Web Security Appliance. In total, 41 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-6407?

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-2016-6407 published?

CVE-2016-6407 was published on 2016-09-17 and last updated on 2026-06-17.

CVE-2016-6407

CVE-2016-6407 is a high-severity vulnerability in Cisco Web 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-399.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (83rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-399
Affected product: Cisco Web Security Appliance
Published: 2016-09-17
Last modified: 2026-06-17

Description

Cisco AsyncOS through 9.5.0-444 on Web Security Appliance (WSA) devices allows remote attackers to cause a denial of service (link saturation) by making many HTTP requests for overlapping byte ranges simultaneously, aka Bug ID CSCuz27219.

Frequently asked questions

What is CVE-2016-6407?: Cisco AsyncOS through 9.5.0-444 on Web Security Appliance (WSA) devices allows remote attackers to cause a denial of service (link saturation) by making many HTTP requests for overlapping byte ranges simultaneously, aka Bug ID CSCuz27219.
How severe is CVE-2016-6407?: CVE-2016-6407 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 none, and availability high.
Is CVE-2016-6407 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-6407?: CVE-2016-6407 primarily affects Cisco Web Security Appliance. In total, 41 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-6407?: 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-2016-6407 published?: CVE-2016-6407 was published on 2016-09-17 and last updated on 2026-06-17.

References

Affected products (41)

cpe:2.3:a:cisco:web_security_appliance:5.6.0-623:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:6.0.0-000:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:7.1.0:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:7.1.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:7.1.2:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:7.1.3:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:7.1.4:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:7.5.0-000:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:7.5.0-825:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:7.5.1-000:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:7.5.2-000:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:7.5.2-hp2-303:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:7.7.0-000:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:7.7.0-608:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:7.7.1-000:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:7.7.5-835:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.0.0-000:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.0.5:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.0.6:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.0.6-078:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.0.6-119:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.0.7:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.0.7-142:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.0.8-mr-113:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.5.0-497:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.5.0.000:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.5.1-021:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.5.2-024:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.5.2-027:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.5.3-055:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.8.0-000:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:8.8.0-085:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:9.0.0-193:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:9.0_base:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:9.1.0-000:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:9.1.0-070:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:9.1_base:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:9.5.0-235:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:9.5.0-284:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:9.5.0-444:*:*:*:*:*:*:*

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