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CVE-2021-1353

26
FAUCET Score

CVE-2021-1353 is a high-severity denial-of-service vulnerability in Cisco StarOS and related products (ASR 5000, 5500, 5700, and Virtualized Packet Core Single Instance). An unauthenticated, remote attacker can exploit a memory leak during IPv4 packet processing by sending crafted packets, leading to an unexpected restart of the npusim process and a DoS condition. The vulnerability has a CVSS score of 8.6 (High) due to its network-based attack vector, low attack complexity, and high impact on availability. Currently, there is no evidence of active exploitation, no public exploit code (Metasploit, Nuclei, ExploitDB), and minimal community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 21.22.0CPE matchmatch criteria
cpe:2.3:o:cisco:staros:*:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:cisco:virtualized_packet_core-single_instance:-:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.8MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.28%
Probability of exploitation in next 30 days
EPSS Percentile
67.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0128 is in the 47th percentile among its peer group of 51,506 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

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/content/CiscoSecurityAdvisory/cisco-sa-asr-mem-leak-dos-MTWGHKk3
Vendor Advisory