CVE intelligence and bounded remediation

CVE-2023-45239 — Facebook Tac Plus security vulnerability

Critical CVSS 9.8

A lack of input validation exists in tac_plus prior to commit 4fdf178 which, when pre or post auth commands are enabled, allows an attacker who can control the username, rem-addr, or NAC address sent to tac_plus to inject shell commands and gain remote code execution on the tac_plus server.

Severity
Critical
CVSS
9.8 (3.1)
Published
2023-10-06
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-790

Affected products

  • facebook / tac_plus
  • fedoraproject / fedora / 39

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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