CVE-2021-1353Network attack vector

Service interruption via IPv4 packet memory leak

Published Jan 20, 2021 · Updated Nov 12, 2024

Denial of service in Cisco StarOS before 21.22.0 allows remote attackers to restart npusim through crafted IPv4 transit traffic. IPv4 packet processing leaks memory for each crafted packet instead of releasing the allocation, eventually exhausting available memory and restarting npusim. Exploitation requires VPP to be enabled, which is not the default, and interrupts packet-processing service without reported data disclosure or modification.

CVSS severity5.8
Medium
EPSS probability1.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Cisco StarOS before 21.22.0 allows remote attackers to restart npusim through crafted IPv4 transit traffic. IPv4 packet processing leaks memory for each crafted packet instead of releasing the allocation, eventually exhausting available memory and restarting npusim. Exploitation requires VPP to be enabled, which is not the default, and interrupts packet-processing service without reported data disclosure or modification.

The record

CVE
CVE-2021-1353
Published
Jan 20, 2021
Updated
Nov 12, 2024
Vendor
ClamAV
Product
Cisco ASR 5000 Series Software
Classifications
CWE-401, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 20, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 12, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco ASR 5000 Series Softwareversion=n/a

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
8.6NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
5.8CiscoCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-401Missing Release of Memory after Effective Lifetime
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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