CVE-2023-54279 in Linux
Summary
by MITRE • 12/30/2025
In the Linux kernel, the following vulnerability has been resolved:
MIPS: fw: Allow firmware to pass a empty env
fw_getenv will use env entry to determine style of env, however it is legal for firmware to just pass a empty list.
Check if first entry exist before running strchr to avoid null pointer dereference.
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Analysis
by VulDB Data Team • 04/27/2026
The vulnerability CVE-2023-54279 represents a null pointer dereference issue within the Linux kernel's firmware handling subsystem specifically affecting MIPS architecture implementations. This flaw exists in the fw_getenv function which processes environment variables passed from firmware components. The vulnerability stems from inadequate input validation when processing firmware environment variable lists, creating a potential crash condition that could be exploited to disrupt system operations.
The technical implementation of this vulnerability occurs in the MIPS firmware subsystem where the fw_getenv function attempts to determine the environment variable style by examining env entries. When firmware passes an empty environment variable list, the function fails to validate whether the first entry exists before invoking the strchr function. This direct dereference of a potentially null pointer results in an immediate system crash or panic, effectively causing a denial of service condition that impacts the entire system's stability and operational continuity.
From an operational impact perspective, this vulnerability poses significant risks to embedded systems and network infrastructure devices that rely on MIPS architecture and firmware-based environment variable handling. The null pointer dereference can lead to complete system crashes, requiring manual intervention for recovery and potentially enabling attackers to exploit the instability for more severe attacks. Systems utilizing this kernel version may experience unexpected downtime and service disruption, particularly in mission-critical environments where continuous operation is essential for business continuity.
The vulnerability aligns with CWE-476 which specifically addresses null pointer dereference conditions in software implementations. Additionally, this issue relates to ATT&CK technique T1499.001 which involves disruption of services through system resource exhaustion or instability. The flaw demonstrates poor defensive programming practices where input validation is insufficient to handle edge cases in firmware communication protocols, creating exploitable conditions that violate fundamental security principles of robust error handling and memory safety.
Mitigation strategies should focus on implementing proper input validation before function calls that require specific data structures. Kernel updates addressing this vulnerability should be prioritized across all affected systems, particularly those running MIPS-based embedded devices or network infrastructure components. System administrators should also consider implementing monitoring solutions to detect potential exploitation attempts and establish automated recovery procedures to minimize service disruption. The fix requires modifications to the fw_getenv function to check for the existence of the first environment variable entry before proceeding with string operations, thereby preventing the null pointer dereference condition that leads to system crashes and denial of service scenarios.