Linux Kernel up to 7.2.5 NTFS ntfs_ir_to_ib heap-based overflow

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.2.5. It has been rated as very critical. This vulnerability affects the function ntfs_ir_to_ib of the component NTFS. This manipulation causes heap-based overflow. This vulnerability is handled as CVE-2026-90133. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 7.2.5 and classified as very critical. Affected by this vulnerability is the function ntfs_ir_to_ib of the component NTFS. The manipulation with an unknown input leads to a heap-based overflow vulnerability. The CWE definition for the vulnerability is CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: ntfs: Fix index_root heap OOB write in ntfs_ir_to_ib() ntfs_ir_to_ib copies all entries from index_root into a freshly allocated index_block_size-byte buffer without verifying that the entries fit in the available space. The entries in index_root may be larger than the usable entry space in the index block. This can cause OOB writes past the end of the allocation. The validator ntfs_index_root_inconsistent() checks that entries are self-consistent within the IR value, but never cross-checks them against index_block_size. There is no bounds check in ntfs_ir_to_ib() before the memcpy. Fixing this at the sink in ntfs_ir_to_ib() since ntfs_index_root_inconsistent() validates the logical consistency of index_root as a structure and a root with large entries is a structurally valid root. The bug is a size conflict of ntfs_ir_to_ib(). Also, the validator is called once per inode load in ntfs_read_locked_inode() while ntfs_ir_to_ib() is only called during a reparent, a check there adds no overhead to the common path. Moreover, even a future call path that bypasses the validator would still be protected. With NULL as first parameter of ntfs_error(), the volume error flag is never set by this call, so the device name will be absent from the error message. In any case, that the caller, ntfs_ir_reparent(), prints an error message that includes the device name on NULL returns. I think this is the best solution available without adding 'struct super_block *sb' as a parameter to ntfs_ir_to_ib(). This heap out-of-bounds write is triggered by a crafted filesystem image, which is not in the kernel threat model, anyway, fixing memory errors would be nice to keep things secure.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-90133 since 09/11/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation needs additional levels of successful authentication. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 09/17/2026).

Upgrading to version 7.2.6 or 7.3-rc1 eliminates this vulnerability. Applying the patch 825dec5120933e90c54e30e31ccfa6c3449043a8/dc09bf79b76f9a7157e225f449655f3f62f96c9c is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5

License

• open-source

Website

• Vendor: https://www.kernel.org/

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