CVE-2021-1377

mediumpriority · track · 24EPSS 0.015 · 74 %ileEURUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
1.48% (74th) EPSS
CVSS 5 · medium
Is it mine?
624 products
Check your exposure
Who says so?
4 sources
cnnvd · enisa_euvd · fstec_bdu · cisco_csaf

EPSS · scored 2026-10-27

A vulnerability in Address Resolution Protocol (ARP) management of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to prevent an affected device from resolving ARP entries for legitimate hosts on the connected subnets. This vulnerability exists because ARP entries are mismanaged. An attacker could exploit this vulnerability by continuously sending traffic that results in incomplete ARP entries. A successful exploit could allow the attacker to cause ARP requests on the device to be unsuccessful for legitimate hosts, resulting in a denial of service (DoS) condition.

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

02

cvss

Technical severity, 0–10. One row per scoring source.

5.8
010

base score 0–10 · higher = more severe · hover a vector to decode

v2.05mediumAV:N/AC:L/Au:N/C:N/I:N/A:Pprimary · NVD / NIST USexploitability 10 · impact 2.9
v3.15.8mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Lprimary · NVD / NIST USexploitability 3.9 · impact 1.4
v3.15.8mediumAV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Lsecondary · FSTEC (BDU) RU
v3.15.8mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Lsecondary · ENISA EU
v3.15.8mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Lsecondary · psirt@cisco.com USexploitability 3.9 · impact 1.4
v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L/E:Usecondary · CVSS-BT (t0sche)
v3.15.8mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Lsecondary · Cisco PSIRT US
03

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS
04

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-399USCWE-399US
05

affected products (624)

Products and version ranges known to be affected.

showing 20 of 624
06

advisories (1)

Vendor and ecosystem advisories describing this.

  • cisco-sa-arp-mtfhBfjECisco IOS and IOS XE Software ARP Resource Management Exhaustion Denial of Service Vulnerability2021-03-24csaf · cisco_csafUS

    A vulnerability in Address Resolution Protocol (ARP) management of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to prevent an affected device from resolving ARP entries for legitimate hosts on the connected subnets. This vulnerability exists because ARP entries are mismanaged. An attacker could exploit this vulnerability by continuously sending traffic that results in incomplete ARP entries. A successful exploit could allow the attacker to cause ARP requests on the device to be unsuccessful for legitimate hosts, resulting in a denial of service (DoS) condition. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

07

also known as (4)

Other names and identifiers for this entity.

08

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bducisco_csafNVDCVE.orgMITRE
published 2021-03-24modified 2026-06-17
09

references (5)

External citations — patches, advisories, analysis.

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