How severe is CVE-2016-6393?

CVE-2016-6393 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-2016-6393 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-6393?

CVE-2016-6393 primarily affects Cisco Ios. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-6393?

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-2016-6393 published?

CVE-2016-6393 was published on 2016-10-05 and last updated on 2026-06-17.

CVE-2016-6393

CVE-2016-6393 is a high-severity vulnerability in Cisco Ios 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: 7.1
EPSS exploit prediction: 5% (91st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-399
Affected product: Cisco Ios
Published: 2016-10-05
Last modified: 2026-06-17

Description

The AAA service in Cisco IOS 12.0 through 12.4 and 15.0 through 15.6 and IOS XE 2.1 through 3.18 and 16.2 allows remote attackers to cause a denial of service (device reload) via a failed SSH connection attempt that is mishandled during generation of an error-log message, aka Bug ID CSCuy87667.

Frequently asked questions

What is CVE-2016-6393?: The AAA service in Cisco IOS 12.0 through 12.4 and 15.0 through 15.6 and IOS XE 2.1 through 3.18 and 16.2 allows remote attackers to cause a denial of service (device reload) via a failed SSH connection attempt that is mishandled during generation of an error-log message, aka Bug ID CSCuy87667.
How severe is CVE-2016-6393?: CVE-2016-6393 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-2016-6393 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-6393?: CVE-2016-6393 primarily affects Cisco Ios. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-6393?: 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-2016-6393 published?: CVE-2016-6393 was published on 2016-10-05 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:o:cisco:ios:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.2:*:*:*:*:*:*:*

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