CVE intelligence and bounded remediation

CVE-2018-0123 — Cisco Ios security vulnerability

Medium CVSS 5.5

A Path Traversal vulnerability in the diagnostic shell for Cisco IOS and IOS XE Software could allow an authenticated, local attacker to use certain diagnostic shell commands that can overwrite system files. These system files may be sensitive and should not be able to be overwritten by a user of the diagnostic shell. The vulnerability is due to lack of proper input validation for certain diagnostic shell commands. An attacker could exploit this vulnerability by authenticating to the device, entering the diagnostic shell, and providing crafted user input to commands at the local diagnostic shell CLI. Successful exploitation could allow the attacker to overwrite system files that should be restricted. Cisco Bug IDs: CSCvg41950.

Severity
Medium
CVSS
5.5 (3.0)
Published
2018-02-08
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-22

Affected products

  • cisco / ios / 16.7(1)
  • cisco / ios_xe

Matched remediation archetype

Path traversal, unsafe upload, and file handling

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Check exposure

  • Trace untrusted filenames, archive entries, URLs, and path segments into read, write, include, extraction, and upload operations.
  • Identify filesystem roots, mount permissions, symbolic-link behavior, archive handling, and whether uploaded content is web-accessible or executable.
  • Review canonicalization and containment checks across supported operating systems and storage backends.

Remediate safely

  • Generate server-side storage identifiers and resolve paths beneath a fixed root using filesystem-aware containment checks.
  • Reject absolute, parent-relative, alternate-separator, device, link, and archive entries that escape the intended root.
  • Store uploads outside executable or served paths, validate type and size, and use private atomic temporary files.

Authoritative sources

Complete CVE record and remediation plan

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