CVE-2026-43110 in Linux
Summary
by MITRE • 05/06/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: brcmfmac: validate bsscfg indices in IF events
brcmf_fweh_handle_if_event() validates the firmware-provided interface index before it touches drvr->iflist[], but it still uses the raw
bsscfgidx field as an array index without a matching range check.
Reject IF events whose bsscfg index does not fit in drvr->iflist[]
before indexing the interface array.
[add missing wifi prefix]
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Analysis
by VulDB Data Team • 06/09/2026
The vulnerability in question affects the brcmfmac driver within the Linux kernel, specifically addressing a flaw in how interface events are processed for Broadcom wireless network adapters. This issue resides in the firmware event handling mechanism where the driver receives notifications from the wireless firmware about interface state changes. The brcmf_fweh_handle_if_event function demonstrates a critical gap in input validation that could potentially allow for arbitrary memory access or manipulation through crafted firmware events.
The technical flaw manifests as a missing range validation check for the bsscfgidx field that originates from firmware-provided interface events. While the driver correctly validates the firmware-provided interface index against the expected range before accessing the drvr->iflist[] array, it fails to perform the same validation when using the raw bsscfgidx field as an array index. This inconsistency creates a potential path for out-of-bounds memory access where an attacker could craft malicious firmware events with invalid bsscfgidx values that exceed the bounds of the interface list array, potentially leading to memory corruption or information disclosure.
The operational impact of this vulnerability extends beyond simple memory corruption, as it represents a classic buffer over-read condition that could be exploited by a malicious actor with control over the wireless firmware. The flaw aligns with CWE-129 Input Validation and CWE-787 Out-of-bounds Write patterns, where inadequate validation of array indices allows for unauthorized memory access. In the context of the ATT&CK framework, this vulnerability could be leveraged as part of a broader attack chain under the T1059 Command and Scripting Interpreter and T1566 Phishing with Malicious Attachments techniques, particularly when combined with other wireless attack vectors.
The mitigation strategy involves implementing proper bounds checking for the bsscfgidx field before using it as an array index into the drvr->iflist[] array. This requires validating that the firmware-provided bsscfgidx value falls within the acceptable range of valid interface configuration indices that correspond to the driver's allocated interface list. The fix ensures that IF events with invalid bsscfgidx values are rejected before any array access occurs, preventing potential exploitation while maintaining normal wireless functionality. This approach aligns with secure coding practices that emphasize defensive programming and input validation as primary defenses against memory corruption vulnerabilities. The resolution addresses the specific gap in the firmware event handling code where the validation logic was applied inconsistently, creating a potential attack surface that could be exploited to compromise the stability and security of wireless network operations.