CVE intelligence and bounded remediation

CVE-2019-9503 — The Broadcom brcmfmac WiFi driver prior to commit a4176ec356c73a46c07c181c6d04039fafa34a9f is vulnerable to a frame validation bypass

High CVSS 8.3

The Broadcom brcmfmac WiFi driver prior to commit a4176ec356c73a46c07c181c6d04039fafa34a9f is vulnerable to a frame validation bypass. If the brcmfmac driver receives a firmware event frame from a remote source, the is_wlc_event_frame function will cause this frame to be discarded and unprocessed. If the driver receives the firmware event frame from the host, the appropriate handler is called. This frame validation can be bypassed if the bus used is USB (for instance by a wifi dongle). This can allow firmware event frames from a remote source to be processed. In the worst case scenario, by sending specially-crafted WiFi packets, a remote, unauthenticated attacker may be able to execute arbitrary code on a vulnerable system. More typically, this vulnerability will result in denial-of-service conditions.

Severity
High
CVSS
8.3 (3.1)
Published
2020-01-16
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-20

Affected products

  • broadcom / brcmfmac_driver
  • redhat / enterprise_linux / 6.0
  • redhat / enterprise_linux / 7.0

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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