CyberSecBulletin
CVE-2026-64532NVD status: Analyzed

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-64532 is a high-severity out-of-bounds write vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists versions b20e5a709d8bd190d6e4645606763c7423e694c1, d41b382068ca4e64e421f736cdd700095464b6ac, 429d653ca641d38a78609b8f62e81a0a5c780a2d as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.13% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to b20e5a709d8bd190d6e4645606763c7423e694c1 or d41b382068ca4e64e421f736cdd700095464b6ac or 429d653ca641d38a78609b8f62e81a0a5c780a2d or 315d3a9a48b49f889da3d858a9307e677cb9e1bd, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.15.212 or 6.1.178 or 6.6.145 or 6.12.97, whichever matches your release line, or a later version.
  3. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxb46acd6a6a627d876898e1c84d3f84902264b445 up to, but not including, b20e5a709d8bd190d6e4645606763c7423e694c1; b46acd6a6a627d876898e1c84d3f84902264b445 up to, but not including, d41b382068ca4e64e421f736cdd700095464b6ac; b46acd6a6a627d876898e1c84d3f84902264b445 up to, but not including, 429d653ca641d38a78609b8f62e81a0a5c780a2d; b46acd6a6a627d876898e1c84d3f84902264b445 up to, but not including, 315d3a9a48b49f889da3d858a9307e677cb9e1bd; b46acd6a6a627d876898e1c84d3f84902264b445 up to, but not including, be306b8d9143a9c076c804a7ca025d69caf9c448; b46acd6a6a627d876898e1c84d3f84902264b445 up to, but not including, 36feda687afebae24c472202694448738809c411; b46acd6a6a627d876898e1c84d3f84902264b445 up to, but not including, 3e127829e57f5190f612412ece4541cb96d5ec7a; 5.15b20e5a709d8bd190d6e4645606763c7423e694c1, d41b382068ca4e64e421f736cdd700095464b6ac, 429d653ca641d38a78609b8f62e81a0a5c780a2d, 315d3a9a48b49f889da3d858a9307e677cb9e1bd, be306b8d9143a9c076c804a7ca025d69caf9c448, 36feda687afebae24c472202694448738809c411
LinuxLinux Kernel5.15 up to, but not including, 5.15.212; 5.16 up to, but not including, 6.1.178; 6.2 up to, but not including, 6.6.145; 6.7 up to, but not including, 6.12.97; 6.13 up to, but not including, 6.18.40; 6.19 up to, but not including, 7.1.55.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40, 7.1.5

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
RequiredA user must take an action such as opening a file or link.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: bound NTFS_DE view.data_off in UpdateRecordData{Root,Allocation} In do_action()'s UpdateRecordDataRoot (fslog.c:3489) and UpdateRecordDataAllocation (fslog.c:3697) cases, the memmove destination is `Add2Ptr(e, le16_to_cpu(e->view.data_off))`, where e->view.data_off comes from an on-disk NTFS_DE inside an INDEX_ROOT or INDEX_BUFFER. Neither case validates view.data_off + dlen against e->size; the existing check_if_index_root / check_if_alloc_index helpers walk the entry chain and validate the entry's offset, but not its internal view fields. The neighbouring read sites (e.g., fs/ntfs3/index.c when iterating view entries) check view.data_off + view.data_size <= e->size. Apply the same bound at the two memmove sites. Reproduced under UML+KASAN on mainline 8d90b09e6741 via pr_warn-only probe instrumentation: with view.data_off forced to 0xFFFC, the memmove writes 32 bytes past the end of the NTFS_DE. This is similar in shape to Pavitra Jha's 2026-05-02 patch "fs/ntfs3: prevent oob in case UpdateRecordDataRoot" (<[email protected]>) which proposes calling ntfs3_bad_de_range(); that helper does not exist in mainline. This patch uses inline checks.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Out-of-bounds Write vulnerabilities (CWE-787)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Write vulnerabilities

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