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CVE-2018-0421

28
FAUCET Score

CVE-2018-0421 is a high-severity denial-of-service vulnerability affecting Cisco Prime Access Registrar products. It stems from improper handling of TCP SYN packets, leading to unreleased file descriptors and eventual application restarts. An unauthenticated, remote attacker can exploit this with low complexity by sending a crafted stream of SYN packets. While no public exploit code or active exploitation has been observed, the vulnerability has received some community and media attention.

Impacted Technologies

VendorProductVersion(s)CPE
>= 7.3, < 7.3.0.4CPE matchmatch criteria
cpe:2.3:a:cisco:prime_access_registrar:*:*:*:*:*:*:*:*
>= 8.0, < 8.0.1.1CPE matchmatch criteria
cpe:2.3:a:cisco:prime_access_registrar:*:*:*:*:*:*:*:*
>= 7.3, < 7.3.0.4CPE matchmatch criteria
cpe:2.3:a:cisco:prime_access_registrar_jumpstart:*:*:*:*:*:*:*:*
>= 8.0, < 8.0.1.1CPE matchmatch criteria
cpe:2.3:a:cisco:prime_access_registrar_jumpstart:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

8.6HIGH

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
4.0
CvssVersion
3.0

Exploit Intelligence

EPSS Score
3.48%
Probability of exploitation in next 30 days
EPSS Percentile
87.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0348 is in the 78th percentile among its peer group of 51,551 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

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/content/CiscoSecurityAdvisory/cisco-sa-20180905-cpar-dos
Vendor Advisory
securityfocus.com / bid/105282
Third Party AdvisoryVDB Entry
securitytracker.com / id/1041684
Third Party AdvisoryVDB Entry