CVE intelligence and bounded remediation

CVE-2023-48643 — Shrubbery tac_plus 2.x, 3.x

Critical CVSS 9.8

Shrubbery tac_plus 2.x, 3.x. and 4.x through F4.0.4.28 allows unauthenticated Remote Command Execution. The product allows users to configure authorization checks as shell commands through the tac_plus.cfg configuration file. These are executed when a client sends an authorization request with a username that has pre-authorization directives configured. However, it is possible to inject additional commands into these checks because strings from TACACS+ packets are used as command-line arguments. If the installation lacks a a pre-shared secret (there is no pre-shared secret by default), then the injection can be triggered without authentication. (The attacker needs to know a username configured to use a pre-authorization command.) NOTE: this is related to CVE-2023-45239 but the issue is in the original Shrubbery product, not Meta's fork.

Severity
Critical
CVSS
9.8 (3.1)
Published
2024-05-16
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-94

Affected products

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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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