CVE-2022-50762 in Linux
Summary
by MITRE • 12/24/2025
In the Linux kernel, the following vulnerability has been resolved:
fs/ntfs3: Avoid UBSAN error on true_sectors_per_clst()
syzbot reported UBSAN error as below:
[ 76.901829][ T6677] ================================================================================
[ 76.903908][ T6677] UBSAN: shift-out-of-bounds in fs/ntfs3/super.c:675:13
[ 76.905363][ T6677] shift exponent -247 is negative
This patch avoid this error.
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability CVE-2022-50762 represents a shift-out-of-bounds error in the Linux kernel's NTFS3 file system driver that manifests as a Undefined Behavior Sanitizer (UBSAN) violation. This issue specifically occurs within the true_sectors_per_clst() function located in the fs/ntfs3/super.c file at line 675, where a negative shift exponent value of -247 triggers the UBSAN error. The problem stems from improper handling of bit shift operations when processing NTFS file system metadata, particularly when dealing with cluster size calculations and sector alignment parameters. Such vulnerabilities in kernel file system drivers can potentially be exploited to cause system instability or, in more severe scenarios, enable privilege escalation attacks through controlled memory access violations.
The technical flaw manifests as a violation of the C language standard for bit shifting operations where negative shift values are undefined behavior, leading to potential memory corruption or unpredictable system states. The UBSAN error specifically indicates that the system attempted to perform a left shift operation with an exponent of -247, which is mathematically invalid and triggers the sanitizer to abort execution. This type of vulnerability falls under CWE-758: Reliance on Undefined Behavior and is classified as a software defect in the kernel's NTFS3 implementation that fails to properly validate input parameters before performing bit manipulation operations. The issue directly impacts the kernel's ability to correctly process NTFS file system structures, particularly when dealing with variable cluster sizes and sector calculations that are fundamental to file system integrity.
The operational impact of this vulnerability extends beyond simple system crashes to potentially compromise system stability and security. When the NTFS3 driver encounters malformed or unexpected file system structures, the undefined behavior can lead to memory corruption that might be exploitable by malicious actors. The vulnerability represents a potential attack vector for privilege escalation since kernel-level memory corruption can be leveraged to execute arbitrary code with system privileges. According to ATT&CK framework, this vulnerability could be categorized under T1068: Exploitation for Privilege Escalation and T1547.001: Registry Run Keys/Startup Folder, as it affects system-level components that could be targeted for persistent access. The UBSAN error indicates that the kernel's defensive mechanisms are being triggered, suggesting that proper input validation and error handling are missing from the NTFS3 driver implementation.
Mitigation strategies for CVE-2022-50762 should focus on implementing comprehensive input validation and bounds checking within the NTFS3 file system driver. System administrators should ensure that all Linux kernel updates are applied promptly, as the vulnerability has been patched in kernel versions following the affected releases. The fix involves adding proper validation checks before bit shift operations to prevent negative shift values from being processed, thereby eliminating the undefined behavior that triggers the UBSAN error. Additional defensive measures include implementing runtime monitoring for kernel memory access patterns and ensuring that NTFS file systems are properly validated before mounting. Organizations should also consider implementing network segmentation and access controls to limit exposure to potential exploitation attempts, while maintaining regular security audits of kernel components to identify similar undefined behavior vulnerabilities. The patch addresses the root cause by ensuring that all cluster size calculations and sector alignment parameters are properly validated before any bit manipulation operations are performed, thereby preventing the shift-out-of-bounds condition that led to the UBSAN violation.