CVE intelligence and bounded remediation

CVE-2021-1390 — Cisco Ios Xe security vulnerability

High CVSS 7.2

A vulnerability in one of the diagnostic test CLI commands of Cisco IOS XE Software could allow an authenticated, local attacker to execute arbitrary code on an affected device. To exploit this vulnerability, the attacker would need to have valid user credentials at privilege level 15. This vulnerability exists because the affected software permits modification of the run-time memory of an affected device under specific circumstances. An attacker could exploit this vulnerability by authenticating to the affected device and issuing a specific diagnostic test command at the CLI. A successful exploit could trigger a logic error in the code that was designed to restrict run-time memory modifications. The attacker could take advantage of this logic error to overwrite system memory locations and execute arbitrary code on the underlying Linux operating system (OS) of the affected device.

Severity
High
CVSS
7.2 (2.0)
Published
2021-03-24
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-123

Affected products

  • cisco / ios_xe / 16.8.1
  • cisco / ios_xe / 16.8.1a
  • cisco / ios_xe / 16.8.1b
  • cisco / ios_xe / 16.8.1c
  • cisco / ios_xe / 16.8.1d
  • cisco / ios_xe / 16.8.1e

Showing 6 representative product identities from 74 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Command, code, expression, and template injection

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Check exposure

  • Trace untrusted values to process execution, interpreters, evaluators, template engines, dynamic imports, and administrative scripting features.
  • Determine whether the affected path is reachable across each trust boundary and which service account or host privilege it inherits.
  • Review configuration for optional execution features, unsafe compatibility modes, and shell invocation.

Remediate safely

  • Replace string-built commands or evaluated code with fixed operations and structured argument APIs that do not invoke a shell.
  • Use strict allowlists for operation identifiers and reject unexpected input before it reaches any interpreter.
  • Update the affected component and add inert regression tests covering metacharacters, encoding variants, and alternate request paths.

Authoritative sources

Complete CVE record and remediation plan

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