CVE-2015-6403

What it is

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.

At a glance

Exploitability

Can be exploited locally on the machine without logging in. High risk of data exposure, data tampering, service disruption.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2015-12-15 05:59 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 00:30 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.4% in the next 30 days (EPSS).
• Severity: 7.2 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2015-12-15 05:59 UTC

Last modified

2026-06-17 00:30 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-20 · Improper input validation

Record status

Modified

Affected

• Cisco spa500 Firmware 7.5.7
• Cisco spa300 Firmware 7.5.7

Attack profile CVSS 2.0 · 7.2

Attack vector

Local

Complexity

Low

Authentication

None

Confidentiality

Complete

Integrity

Complete

Availability

Complete

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2015-6403.md and follow it. Check whether this project is affected by CVE-2015-6403. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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