CVE intelligence and bounded remediation

CVE-2019-20217 — Dlink Dir-859 Firmware security vulnerability

Critical CVSS 9.8

D-Link DIR-859 1.05 and 1.06B01 Beta01 devices allow remote attackers to execute arbitrary OS commands via the urn: to the M-SEARCH method in ssdpcgi() in /htdocs/cgibin, because SERVER_ID is mishandled. The value of the urn: service/device is checked with the strstr function, which allows an attacker to concatenate arbitrary commands separated by shell metacharacters.

Severity
Critical
CVSS
9.8 (3.1)
Published
2020-01-29
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-78

Affected products

  • dlink / dir-859_firmware / 1.05
  • dlink / dir-859_firmware / 1.06b01

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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