CVE-2023-54135 in Linux
Summary
by MITRE • 12/24/2025
In the Linux kernel, the following vulnerability has been resolved:
maple_tree: fix potential out-of-bounds access in mas_wr_end_piv()
Check the write offset end bounds before using it as the offset into the pivot array. This avoids a possible out-of-bounds access on the pivot array if the write extends to the last slot in the node, in which case the node maximum should be used as the end pivot.
akpm: this doesn't affect any current callers, but new users of mapletree may encounter this problem if backported into earlier kernels, so let's fix it in -stable kernels in case of this.
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Analysis
by VulDB Data Team • 01/03/2026
The vulnerability CVE-2023-54135 resides within the Linux kernel's maple tree implementation, specifically in the mas_wr_end_piv() function that handles write operations on memory mappings. This issue represents a classic out-of-bounds memory access flaw that could potentially lead to system instability or security compromise. The maple tree data structure serves as a critical component in kernel memory management, particularly for handling large memory ranges and mapping operations. The vulnerability manifests when processing write operations that extend to the boundary of memory nodes, creating a scenario where improper bounds checking could result in accessing memory outside the intended allocation boundaries.
The technical flaw occurs in the pivot array access mechanism where the system fails to properly validate the write offset end bounds before using them as indices into the pivot array. When a write operation extends to the last slot in a memory node, the system should utilize the node maximum value as the end pivot rather than allowing the potentially invalid offset to be used directly. This represents a boundary condition error that violates fundamental memory safety principles and can be classified as a CWE-129: Improper Validation of Array Index. The flaw demonstrates how seemingly minor boundary checking deficiencies can create significant security implications within kernel-level data structures.
The operational impact of this vulnerability extends beyond simple system instability to potentially enable privilege escalation or denial of service conditions. While the kernel maintainers note that this doesn't affect current callers, the nature of the vulnerability means that any new implementations or backported code utilizing the maple tree functionality could be susceptible to this issue. The vulnerability affects the -stable kernel releases, indicating that it represents a regression or previously undetected flaw that requires immediate attention. Attackers could potentially exploit this by crafting specific memory mapping operations that trigger the boundary condition, leading to memory corruption that might be leveraged for privilege escalation or system compromise.
Mitigation strategies for CVE-2023-54135 focus primarily on applying the kernel patch that implements proper bounds checking before pivot array access. System administrators should prioritize updating to kernel versions that include this fix, particularly in production environments where memory mapping operations are frequent. The fix involves implementing a check that validates write offset end bounds against node maximum values before allowing access to the pivot array. This aligns with ATT&CK technique T1068: Exploitation for Privilege Escalation, as the vulnerability could potentially be exploited to gain elevated privileges through memory corruption. Organizations should also monitor for similar patterns in other kernel data structures and implement comprehensive memory safety testing for all kernel components that handle dynamic memory allocation and indexing operations.