CVE-2026-72200 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
ntfs: detect mapping-pairs LCN accumulator overflow
The NTFS mapping-pairs parser accumulates relative LCN deltas in a signed integer. A corrupted attribute can drive that addition past the representable range.
One corrupt runlist shape sets the accumulated LCN to S64_MAX and then adds a delta of 1 in the next mapping-pairs entry.
Signed overflow is undefined and can turn an invalid runlist into a different set of physical clusters.
Check the LCN addition for overflow before storing the next run.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability under discussion represents a critical integer overflow condition within the NTFS filesystem driver of the Linux kernel, specifically affecting the mapping-pairs parser responsible for interpreting filesystem metadata structures. This flaw resides in the ntfs3 filesystem implementation where the kernel processes runlists that describe the physical location of data clusters on disk. The issue manifests when parsing corrupted NTFS attributes where the mapping-pairs structure contains malformed entries that trigger arithmetic operations beyond the limits of signed 64-bit integers. The vulnerability is classified as a classic integer overflow condition that can lead to unpredictable behavior and potential privilege escalation or denial of service scenarios.
The technical implementation flaw occurs within the runlist parsing logic where relative logical cluster number (LCN) deltas are accumulated in a signed integer variable without proper bounds checking. When processing corrupted filesystem metadata, an attacker-controlled or malformed runlist entry can cause the accumulator to reach S64_MAX (the maximum value of a signed 64-bit integer) and then attempt to add a delta of one, resulting in undefined behavior due to signed integer overflow. According to CWE-190, this represents an integer overflow vulnerability that occurs when a computation produces a result that exceeds the maximum value representable by the target data type. The use of signed arithmetic in this context creates a path where legitimate filesystem corruption can be exploited to manipulate the kernel's interpretation of physical cluster locations.
The operational impact of this vulnerability extends beyond simple denial of service as it represents a potential privilege escalation vector within the kernel space execution environment. When the overflow occurs, the corrupted runlist can be transformed into a different set of physical clusters that may contain sensitive data or allow manipulation of filesystem structures. This behavior aligns with ATT&CK technique T1068 which describes the exploitation of legitimate system privileges through kernel vulnerabilities, and more specifically T1547.001 related to privilege escalation via kernel exploits. The vulnerability affects systems running Linux kernels with NTFS support where filesystem corruption or maliciously crafted NTFS attributes could trigger this condition during normal file access operations.
The mitigation strategy requires implementing proper overflow detection before storing accumulated LCN values, ensuring that arithmetic operations on the signed integer accumulator are checked against valid ranges before being applied to physical cluster calculations. This approach aligns with secure coding practices recommended in CERT Secure Coding Standards and specifically addresses the need for overflow checking in integer arithmetic operations. The fix involves adding bounds checking logic that prevents the accumulation from exceeding representable integer limits, effectively preventing the undefined behavior that would otherwise occur during signed integer overflow conditions. Additionally, the kernel should implement proper validation of runlist structures to detect and reject malformed entries before they can be processed by the vulnerable parsing logic, thereby reducing the attack surface for exploitation through corrupted filesystem metadata.