CVE intelligence and bounded remediation

CVE-2019-9891 — Tldp Advanced Bash-Scripting Guide security vulnerability

Critical CVSS 9.8

The function getopt_simple as described in Advanced Bash Scripting Guide (ISBN 978-1435752184) allows privilege escalation and execution of commands when used in a shell script called, for example, via sudo.

Severity
Critical
CVSS
9.8 (3.0)
Published
2019-05-31
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-94

Affected products

  • tldp / advanced_bash-scripting_guide

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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