CyberSecBulletin
CVE-2026-64296NVD status: Modified

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-64296 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 attacker with a low-privileged account, without any action from a user. The record lists versions 72a2589d82eb001c94b74bcfe6f9a599bd9bef60, fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4, cf85180b8a015029ee147694eaf4e0b3537e9432 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 0.17% 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 72a2589d82eb001c94b74bcfe6f9a599bd9bef60 or fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4 or cf85180b8a015029ee147694eaf4e0b3537e9432 or ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.261 or 5.15.212 or 6.1.178 or 6.6.145, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxca06197382bde0a3bc20215595d1c9ce20c6e341 up to, but not including, 72a2589d82eb001c94b74bcfe6f9a599bd9bef60; ca06197382bde0a3bc20215595d1c9ce20c6e341 up to, but not including, fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4; ca06197382bde0a3bc20215595d1c9ce20c6e341 up to, but not including, cf85180b8a015029ee147694eaf4e0b3537e9432; ca06197382bde0a3bc20215595d1c9ce20c6e341 up to, but not including, ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0; ca06197382bde0a3bc20215595d1c9ce20c6e341 up to, but not including, 727bf7783a2936ffd55c628dddfd69343e511dcf; ca06197382bde0a3bc20215595d1c9ce20c6e341 up to, but not including, 33c0b96d7e1672be1de0053786637ea46fb81507; ca06197382bde0a3bc20215595d1c9ce20c6e341 up to, but not including, c8e041c68c0bbb73aa62371ee63947bb6949d8b2; ca06197382bde0a3bc20215595d1c9ce20c6e341 up to, but not including, 3a1230e7b043c62737b05a3e9275ca83a43ad20a; and 1 more ranges72a2589d82eb001c94b74bcfe6f9a599bd9bef60, fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4, cf85180b8a015029ee147694eaf4e0b3537e9432, ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0, 727bf7783a2936ffd55c628dddfd69343e511dcf, 33c0b96d7e1672be1de0053786637ea46fb81507
LinuxLinux Kernel5.7 up to, but not including, 5.10.261; 5.11 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, 6.12.96; 6.13 up to, but not including, 6.18.39; 6.19 up to, but not including, 7.1.45.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.39

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
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
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:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: exfat: bound uniname advance in exfat_find_dir_entry() In exfat_find_dir_entry(), each TYPE_EXTEND (file name) entry advances the output pointer by a fixed amount while the loop guard only tracks the accumulated name length: if (++order == 2) uniname = p_uniname->name; else uniname += EXFAT_FILE_NAME_LEN; len = exfat_extract_uni_name(ep, entry_uniname); name_len += len; unichar = *(uniname+len); *(uniname+len) = 0x0; uniname grows by EXFAT_FILE_NAME_LEN (15) per name entry, but name_len grows only by the actual extracted length, which is shorter when a name fragment contains an early NUL. The only guard is `name_len >= MAX_NAME_LENGTH`, so a crafted directory with many short name fragments lets uniname run far past the p_uniname->name[MAX_NAME_LENGTH + 3] buffer while name_len stays small, causing an out-of-bounds read and write at *(uniname+len). The sibling extractor exfat_get_uniname_from_ext_entry() already stops on a short fragment (the lockstep `len != EXFAT_FILE_NAME_LEN` guard added in commit d42334578eba ("exfat: check if filename entries exceeds max filename length")); exfat_find_dir_entry() never got the equivalent. Track the per-entry write offset as a count and reject a fragment once the offset, or the offset plus the extracted length, would exceed MAX_NAME_LENGTH, before forming the output pointer.

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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