CVE-2015-4199

What it is

Race condition in the IPv6-to-IPv4 functionality in Cisco IOS 15.3S in the Performance Routing Engine (PRE) module on UBR devices allows remote attackers to cause a denial of service (NULL pointer free and module crash) by triggering intermittent connectivity with many IPv6 CPE devices, aka Bug ID CSCug47366.

At a glance

Exploitability

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

Exploit odds

2.1% chance of exploitation in the next 30 days (EPSS).

Fix

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

Timeline

1. 2015-06-27 10:59 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 00:26 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 2.1% in the next 30 days (EPSS).
• Severity: 7.1 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2015-06-27 10:59 UTC

Last modified

2026-06-17 00:26 UTC

Exploit probability

2.1% · EPSS, next 30 days

Weakness

CWE-362 · Race condition

Record status

Modified

Affected

• Cisco iOS 15.3s

Attack profile CVSS 2.0 · 7.1

Attack vector

Network

Complexity

Medium

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.

Read https://cve-list.com/agent/cve/CVE-2015-4199.md and follow it. Check whether this project is affected by CVE-2015-4199. 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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