CyberSecBulletin
CVE-2026-31716NVD status: Modified

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-31716 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 8e64d33198b5a0fb14a452708bad844f94f03b2c, 1393a467a9607e62123806de7d4c3a3e54e396a9, f90b8a1798b750755a9e9aee66678f0a1820bbaf 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 8e64d33198b5a0fb14a452708bad844f94f03b2c or 1393a467a9607e62123806de7d4c3a3e54e396a9 or f90b8a1798b750755a9e9aee66678f0a1820bbaf or 4b1613d7e2deda831a97e427d1ea586e50fe1be5, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.6.136 or 6.12.84 or 6.18.25 or 7.0.2, 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, 8e64d33198b5a0fb14a452708bad844f94f03b2c; b46acd6a6a627d876898e1c84d3f84902264b445 up to, but not including, 1393a467a9607e62123806de7d4c3a3e54e396a9; b46acd6a6a627d876898e1c84d3f84902264b445 up to, but not including, f90b8a1798b750755a9e9aee66678f0a1820bbaf; b46acd6a6a627d876898e1c84d3f84902264b445 up to, but not including, 4b1613d7e2deda831a97e427d1ea586e50fe1be5; b46acd6a6a627d876898e1c84d3f84902264b445 up to, but not including, 0112e6279420d4005b3d57af36fb45c01b8d0116; b46acd6a6a627d876898e1c84d3f84902264b445 up to, but not including, f79d0403ea20a81bc29105bba54fbcab54e8c403; b46acd6a6a627d876898e1c84d3f84902264b445 up to, but not including, 0ca0485e4b2e837ebb6cbd4f2451aba665a03e4b; 5.158e64d33198b5a0fb14a452708bad844f94f03b2c, 1393a467a9607e62123806de7d4c3a3e54e396a9, f90b8a1798b750755a9e9aee66678f0a1820bbaf, 4b1613d7e2deda831a97e427d1ea586e50fe1be5, 0112e6279420d4005b3d57af36fb45c01b8d0116, f79d0403ea20a81bc29105bba54fbcab54e8c403
LinuxLinux Kernel5.15 up to, but not including, 6.6.136; 6.7 up to, but not including, 6.12.84; 6.13 up to, but not including, 6.18.25; 6.19 up to, but not including, 7.0.2; 7.16.6.136, 6.12.84, 6.18.25, 7.0.2

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: validate rec->used in journal-replay file record check check_file_record() validates rec->total against the record size but never validates rec->used. The do_action() journal-replay handlers read rec->used from disk and use it to compute memmove lengths: DeleteAttribute: memmove(attr, ..., used - asize - roff) CreateAttribute: memmove(..., attr, used - roff) change_attr_size: memmove(..., used - PtrOffset(rec, next)) When rec->used is smaller than the offset of a validated attribute, or larger than the record size, these subtractions can underflow allowing us to copy huge amounts of memory in to a 4kb buffer, generally considered a bad idea overall. This requires a corrupted filesystem, which isn't a threat model the kernel really needs to worry about, but checking for such an obvious out-of-bounds value is good to keep things robust, especially on journal replay Fix this up by bounding rec->used correctly. This is much like commit b2bc7c44ed17 ("fs/ntfs3: Fix slab-out-of-bounds read in DeleteIndexEntryRoot") which checked different values in this same switch statement.

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. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Write vulnerabilities

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