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CVE-2015-4199

19
FAUCET Score

CVE-2015-4199 describes a race condition in the IPv6-to-IPv4 functionality of Cisco IOS 15.3S, specifically within the Performance Routing Engine (PRE) module on UBR devices. This vulnerability allows remote attackers to trigger a denial of service by causing a NULL pointer free and module crash through intermittent connectivity with numerous IPv6 CPE devices. With a CVSS score of 7.1, it is considered high severity, requiring medium attack complexity (AC:M) but no authentication (Au:N), leading to a complete loss of availability (A:C). There is no evidence of active exploitation, publicly available exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
15.3sCPE matchmatch criteria
cpe:2.3:o:cisco:ios:15.3s:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

7.1HIGH

AV:N/AC:M/Au:N/C:N/I:N/A:C

Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
COMPLETE
Access Vector
NETWORK
Access Complexity
MEDIUM
Authentication
NONE
Exploitability Score
8.6
Impact Score
6.9
CvssVersion
2.0

Exploit Intelligence

EPSS Score
2.12%
Probability of exploitation in next 30 days
EPSS Percentile
80.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0212 is in the 37th percentile among its peer group of 8,918 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

ciscovendor investigatingvia nvd_reference
View patch

References

tools.cisco.com / security/center/viewAlert.x
Vendor Advisory
securityfocus.com / bid/75335
Third Party AdvisoryVDB Entry
securitytracker.com / id/1032692
Third Party AdvisoryVDB Entry