CVE intelligence and bounded remediation

CVE-2021-1377 — Cisco Ios security vulnerability

Medium CVSS 5.8

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.

Severity
Medium
CVSS
5.8 (3.1)
Published
2021-03-24
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-399

Affected products

  • cisco / ios / 12.2(6)i1
  • cisco / ios / 15.1(3)svr1
  • cisco / ios / 15.1(3)svr2
  • cisco / ios / 15.1(3)svr3
  • cisco / ios / 15.1(3)svs
  • cisco / ios / 15.1(3)svs1

Showing 6 representative product identities from 302 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Resource exhaustion and denial of service

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Identify attacker-influenced work factors including input size, nesting, compression, fan-out, regex cost, allocation, recursion, retries, and connection lifetime.
  • Map per-request and shared CPU, memory, disk, descriptor, thread, queue, and downstream-service limits.
  • Determine whether authentication, tenancy, quotas, and rate controls apply before expensive processing begins.

Remediate safely

  • Bound input size, nesting, expansion, work, concurrency, queue depth, retries, and execution time before resource-intensive processing.
  • Release resources on every success, error, cancellation, and timeout path and use backpressure instead of unbounded buffering.
  • Update affected components and add small deterministic tests that assert resource ceilings rather than exhausting a host.

Authoritative sources

Complete CVE record and remediation plan

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