CVE-2026-45935: fs/ntfs3: Fix slab-out-of-bounds read in DeleteIndexEntryRoot
In the Linux kernel, the following vulnerability has been resolved:
fs/ntfs3: Fix slab-out-of-bounds read in DeleteIndexEntryRoot
In the 'DeleteIndexEntryRoot' case of the 'do_action' function, the
entry size ('esize') is retrieved from the log record without adequate
bounds checking.
Specifically, the code calculates the end of the entry ('e2') using:
e2 = Add2Ptr(e1, esize);
It then calculates the size for memmove using 'PtrOffset(e2, ...)',
which subtracts the end pointer from the buffer limit. If 'esize' is
maliciously large, 'e2' exceeds the used buffer size. This results in
a negative offset which, when cast to size_t for memmove, interprets
as a massive unsigned integer, leading to a heap buffer overflow.
This commit adds a check to ensure that the entry size ('esize') strictly
fits within the remaining used space of the index header before performing
memory operations.
Security readout for executives and security teams
Plain-English summary
A flaw in Linux’s NTFS3 filesystem driver can corrupt kernel memory when it processes a maliciously sized NTFS log entry. Exploitation requires local access and user interaction according to the supplied CVSS data. Successful triggering could crash the system or potentially compromise confidentiality and integrity, although the sources do not demonstrate a specific exploitation outcome.
Executive priority
Treat as a high-priority kernel update for endpoints, forensic systems, virtualization hosts, and other machines that may process untrusted NTFS content. Broader urgency is lower where NTFS3 is unavailable or strictly isolated, but exposure should be verified rather than assumed.
Technical view
DeleteIndexEntryRoot trusted an entry size from an NTFS log record. An oversized value could move a pointer beyond the used index buffer; the resulting negative offset became a massive unsigned memmove length, causing out-of-bounds kernel heap access. The stable commits add a remaining-space bounds check before memory operations.
Likely exposure
Exposure is most likely where affected Linux kernels use NTFS3 to process attacker-controlled or corrupted NTFS volumes. The bundle identifies affected release points from 5.15 through 7.0, but exact distribution and backport status require vendor verification. No direct network attack path is identified.
Exploitation context
The supplied CVSS is 7.8 with local access, low complexity, no privileges, and user interaction required. The CVE is not marked as KEV, and the cited sources provide no evidence of active exploitation or a public exploit. Absence from KEV does not prove exploitation has never occurred.
Researcher notes
The title describes a slab out-of-bounds read, while the detailed description characterizes the unsafe memmove as a heap buffer overflow. The sources establish faulty bounds handling and memory corruption risk, but do not establish reliable code execution. The simplified affected-version list is insufficient for precise distribution package conclusions.
Mitigation direction
Install a vendor kernel containing the applicable referenced stable fix or confirmed backport.
Consult the Linux distribution’s security advisory for exact package and reboot requirements.
Until patched, restrict processing of untrusted or removable NTFS volumes where operationally feasible.
Prioritize systems where untrusted users can supply NTFS media or disk images.
Validation and detection
Inventory running kernel versions and determine whether NTFS3 is enabled or used.
Compare each distribution kernel build with its vendor advisory and backport status.
Confirm the installed kernel contains the applicable stable fix, then reboot into it.
Review NTFS mount workflows for attacker-controlled physical media, images, or volumes.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Potential ATT&CK relevance
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1CVSS vectors
3Timeline events
0ADP providers
8Source links
CVSS vector scores
1 official score
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