CVE-2015-6391

What it is

Cisco Unified SIP 3905 phones allow remote attackers to cause a denial of service (resource consumption and functionality loss) via a large amount of network traffic, aka Bug ID CSCuh51331.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

1.9% chance of exploitation in the next 30 days (EPSS).

Fix

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

Timeline

1. 2015-12-05 03:59 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: 1.9% in the next 30 days (EPSS).
• Severity: 7.8 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2015-12-05 03:59 UTC

Last modified

2026-06-17 00:30 UTC

Exploit probability

1.9% · EPSS, next 30 days

Weakness

CWE-399

Record status

Modified

Affected

• Cisco Unified Sip Phone 3900 Firmware 8.1\(1b\)
• Cisco Unified Sip Phone 3900 Firmware 8.1\(2\)
• Cisco Unified Sip Phone 3900 Firmware 8.1\(2\)sr1
• Cisco Unified Sip Phone 3900 Firmware 8.1\(3\)
• Cisco Unified Sip Phone 3900 Firmware 8.1\(4\)
• Cisco Unified Sip Phone 3900 Firmware 9.2\(1\)
• Cisco Unified Sip Phone 3900 Firmware 9.2\(2\)

Attack profile CVSS 2.0 · 7.8

Attack vector

Network

Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

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.

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