CVE-2026-63793 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
ntfs: serialize volume label accesses
Protect vol->volume_label with a mutex and snaphost the label before copy_to_user. This prevent a use-after-free when FS_IOC_SETFSLABEL replaces the vol->volume_label and FS_IOC_GETTSLABEL reads it concurrently.
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Analysis
by VulDB Data Team • 07/19/2026
The vulnerability in question affects the ntfs file system implementation within the Linux kernel, specifically addressing a race condition that can lead to use-after-free conditions during concurrent access to volume labels. This issue arises from insufficient synchronization mechanisms when handling volume label operations, creating potential security implications for systems utilizing ntfs file systems. The problem manifests when multiple processes attempt to read and write volume labels simultaneously, exposing the underlying kernel code to memory safety violations.
The technical flaw stems from the lack of proper mutex protection around the vol->volume_label access during concurrent operations. When FS_IOC_SETFSLABEL ioctl command replaces the volume label while FS_IOC_GETFSLABEL attempts to read it, there exists a critical window where the memory location may be freed and reallocated before the read operation completes. This race condition allows for potential memory corruption and arbitrary code execution if malicious actors can manipulate the timing of these concurrent operations. The vulnerability directly relates to CWE-362, which describes race conditions in concurrent programming where multiple threads or processes access shared resources without proper synchronization.
The operational impact of this vulnerability extends beyond simple data corruption, potentially enabling privilege escalation attacks and system instability. Systems running ntfs file systems with concurrent label access operations become vulnerable to exploitation, particularly in environments where automated tools perform simultaneous volume label modifications or queries. The use-after-free condition can be leveraged by attackers to corrupt kernel memory structures, leading to denial of service conditions or more severe security compromises depending on the specific execution context and available attack surface.
Mitigation strategies for this vulnerability involve implementing proper mutex synchronization around all volume label access operations as recommended in the fix. The solution requires protecting the vol->volume_label variable with a dedicated mutex during both read and write operations, ensuring that any snapshot of the label value occurs within the locked context before copying data to user space. This approach aligns with ATT&CK technique T1068 which involves exploiting local privilege escalation vulnerabilities through improper synchronization mechanisms in kernel code. Additional defensive measures include kernel hardening configurations, such as enabling stack canaries and address space layout randomization, along with regular security updates and monitoring for suspicious concurrent file system operations that might indicate exploitation attempts.