CVE-2015-4199 — 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

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HIGH

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

Published Jun 27, 2015

7.1

HIGH

CVSS 2.0

EPSS 2.12%

Description

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.

Affected products

Remediation

No remediation recorded yet.

Metrics

2.12% 0.02124

Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.

EPSS probability 0.02124

Score over time

2022–2026

EPSS v2
EPSS v3
EPSS v4
EPSS v5

Percentile over time

EPSS v2
EPSS v3
EPSS v4
EPSS v5

Table of values (10 key points)

Flat stretches are collapsed; showing up to 120 newest points.

Date	Score	Percentile	Model
Oct 1, 2026	2.12% (0.02124)	81.23th	v5 (v2026.06.15)
Jun 15, 2026	2.12% (0.02124)	79.44th	v5 (v2026.06.15)
Mar 17, 2025	0.95% (0.00950)	74.77th	v4 (v2025.03.14)
Dec 12, 2024	0.24% (0.00240)	62.89th	v3 (v2023.03.01)
Jun 20, 2024	0.24% (0.00240)	62.19th	v3 (v2023.03.01)
Mar 7, 2023	0.24% (0.00240)	60.17th	v3 (v2023.03.01)
Mar 6, 2023	1.14% (0.01136)	59.45th	v2 (v2022.01.01)
Oct 18, 2022	1.14% (0.01136)	58.28th	v2 (v2022.01.01)
Apr 1, 2022	1.14% (0.01136)	56.27th	v2 (v2022.01.01)
Feb 4, 2022	1.14% (0.01136)	34.23th	v2 (v2022.01.01)

Weaknesses (1)

CWE-362

Race Condition

References (3)

http://tools.cisco.com/security/center/viewAlert.x?alertId=39423
vendor-advisoryx_refsource_CISCOVendor Advisory
http://www.securityfocus.com/bid/75335
vdb-entryx_refsource_BIDThird Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1032692
vdb-entryx_refsource_SECTRACKThird Party AdvisoryVDB Entry

Link	Providers	Tags
http://tools.cisco.com/security/center/viewAlert.x?alertId=39423		vendor-advisoryx_refsource_CISCOVendor Advisory
http://www.securityfocus.com/bid/75335		vdb-entryx_refsource_BIDThird Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1032692		vdb-entryx_refsource_SECTRACKThird Party AdvisoryVDB Entry

Change history (0)

No recorded changes yet.

Sources

CVE.org / MITRE

Status PUBLISHED

Assigner cisco

Published Jun 27, 2015

Updated Aug 6, 2024

Reserved Jun 4, 2015

Link CVE-2015-4199

CISA Vulnrichment

Updated n/a

NVD

Status Modified

Modified Jun 17, 2026

Link CVE-2015-4199

Red Hat

Severity n/a

Public date n/a

Links CVE-2015-4199