How severe is CVE-2015-6403?

CVE-2015-6403 has a CVSS 2.0 base score of 7.2, rated high severity.

Is CVE-2015-6403 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2015-6403?

CVE-2015-6403 primarily affects Cisco Spa500 Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2015-6403?

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-2015-6403 published?

CVE-2015-6403 was published on 2015-12-15 and last updated on 2026-06-17.

CVE-2015-6403

CVE-2015-6403 is a high-severity vulnerability in Cisco Spa500 Firmware with a CVSS 2.0 base score of 7.2. 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 2.0 base score 7.2)
EPSS exploit prediction: 0% (30th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Cisco Spa500 Firmware
Published: 2015-12-15
Last modified: 2026-06-17

Description

The TFTP implementation on Cisco Small Business SPA30x, SPA50x, SPA51x phones 7.5.7 improperly validates firmware-image file integrity, which allows local users to load a Trojan horse image by leveraging shell access, aka Bug ID CSCut67400.

Frequently asked questions

What is CVE-2015-6403?: The TFTP implementation on Cisco Small Business SPA30x, SPA50x, SPA51x phones 7.5.7 improperly validates firmware-image file integrity, which allows local users to load a Trojan horse image by leveraging shell access, aka Bug ID CSCut67400.
How severe is CVE-2015-6403?: CVE-2015-6403 has a CVSS 2.0 base score of 7.2, rated high severity.
Is CVE-2015-6403 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2015-6403?: CVE-2015-6403 primarily affects Cisco Spa500 Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2015-6403?: 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-2015-6403 published?: CVE-2015-6403 was published on 2015-12-15 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:o:cisco:spa500_firmware:7.5.7:*:*:*:*:*:*:*
cpe:2.3:o:cisco:spa300_firmware:7.5.7:*:*:*:*:*:*:*

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