CVE-2023-53521 in Linux
Summary
by MITRE • 10/01/2025
In the Linux kernel, the following vulnerability has been resolved:
scsi: ses: Fix slab-out-of-bounds in ses_intf_remove()
A fix for:
BUG: KASAN: slab-out-of-bounds in ses_intf_remove+0x23f/0x270 [ses]
Read of size 8 at addr ffff88a10d32e5d8 by task rmmod/12013
When edev->components is zero, accessing edev->component[0] members is
wrong.
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Analysis
by VulDB Data Team • 01/27/2026
The vulnerability CVE-2023-53521 represents a critical slab out-of-bounds memory access flaw in the Linux kernel's SCSI subsystem, specifically within the SCSI Enclosure Services (SES) driver. This issue manifests during the removal of SES interface components when the kernel attempts to access memory beyond the allocated slab boundaries. The problem occurs in the ses_intf_remove function where the kernel performs a read operation of size 8 at address ffff88a10d32e5d8, triggering a KASAN (Kernel Address Sanitizer) detection. The flaw is particularly dangerous because it demonstrates a classic buffer overflow condition that can lead to kernel memory corruption and potential privilege escalation.
The technical root cause of this vulnerability stems from inadequate bounds checking in the SES driver's component management logic. When the kernel processes SCSI enclosure services interfaces, it maintains an array of components in the edev->component structure. However, the code fails to verify that edev->components contains valid entries before attempting to access edev->component[0]. This condition occurs when the component count is zero, meaning no actual components exist, yet the code proceeds to dereference the array element anyway. This violates fundamental memory safety principles and creates a scenario where the kernel attempts to read from memory that has not been properly allocated or initialized, leading to unpredictable behavior and potential system instability.
The operational impact of CVE-2023-53521 extends beyond simple kernel crashes, as it represents a potential attack vector for privilege escalation and system compromise. When exploited, this vulnerability allows an attacker to trigger kernel memory corruption through the rmmod command, which removes kernel modules from memory. The out-of-bounds access can corrupt kernel data structures, potentially enabling attackers to execute arbitrary code with kernel privileges. This aligns with CWE-129, which describes improper validation of array indices, and demonstrates characteristics consistent with ATT&CK technique T1068, which involves exploiting vulnerabilities to gain elevated privileges. The vulnerability is particularly concerning in environments where unprivileged users can execute rmmod commands or where kernel module loading/unloading is not properly restricted.
Mitigation strategies for CVE-2023-53521 should focus on immediate patch application, as the fix involves adding proper bounds checking before array access. System administrators should prioritize updating their Linux kernel versions to include the patched ses driver implementation that validates edev->components before accessing edev->component[0]. Additional defensive measures include implementing kernel module whitelisting policies, restricting rmmod command execution to authorized users only, and monitoring for suspicious module removal activities. The fix should be complemented by enhanced kernel memory protection mechanisms and regular security auditing of kernel subsystems to identify similar boundary condition vulnerabilities. Organizations should also consider implementing intrusion detection systems that can monitor for anomalous rmmod activities and kernel memory access patterns that might indicate exploitation attempts.