CyberSecBulletin
CVE-2026-64449NVD status: Analyzed

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-64449 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 65358d89dc9f1c25d9364b2b3ef0f3b47717f9ed, adc8b9c30d716c362646edb45662aa1c641a154a, 8eff7cd4817e14dbe3b9952cce55ef52d1d38940 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 0.14% 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 65358d89dc9f1c25d9364b2b3ef0f3b47717f9ed or adc8b9c30d716c362646edb45662aa1c641a154a or 8eff7cd4817e14dbe3b9952cce55ef52d1d38940 or e99f2df433c63c86c93de1e5f08f16e404388756, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.1.178 or 6.6.145 or 6.12.96 or 6.18.39, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxf00a86d98a1ec3e99d352cda926fab767ba43b1f up to, but not including, 65358d89dc9f1c25d9364b2b3ef0f3b47717f9ed; f00a86d98a1ec3e99d352cda926fab767ba43b1f up to, but not including, adc8b9c30d716c362646edb45662aa1c641a154a; f00a86d98a1ec3e99d352cda926fab767ba43b1f up to, but not including, 8eff7cd4817e14dbe3b9952cce55ef52d1d38940; f00a86d98a1ec3e99d352cda926fab767ba43b1f up to, but not including, e99f2df433c63c86c93de1e5f08f16e404388756; f00a86d98a1ec3e99d352cda926fab767ba43b1f up to, but not including, 1b495fa0d4927c88d88bf346bf311f2e26e860ed; f00a86d98a1ec3e99d352cda926fab767ba43b1f up to, but not including, 9f32f38265014fac7f5dc9490fb01a638ce6e121; 2.6.3265358d89dc9f1c25d9364b2b3ef0f3b47717f9ed, adc8b9c30d716c362646edb45662aa1c641a154a, 8eff7cd4817e14dbe3b9952cce55ef52d1d38940, e99f2df433c63c86c93de1e5f08f16e404388756, 1b495fa0d4927c88d88bf346bf311f2e26e860ed, 9f32f38265014fac7f5dc9490fb01a638ce6e121
LinuxLinux Kernel2.6.32 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, 7.1.4; 7.26.1.178, 6.6.145, 6.12.96, 6.18.39, 7.1.4

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: staging: vme_user: bound slave read/write to the kern_buf size The SLAVE-path helpers buffer_to_user() and buffer_from_user() copy 'count' bytes into/out of the fixed-size kern_buf (size_buf == PCI_BUF_SIZE == 0x20000, 128 KiB) using *ppos as the offset, without bounding *ppos + count against size_buf. vme_user_write()/vme_user_read() only clamp count to the VME window size (image_size = vme_get_size(resource)), which VME_SET_SLAVE sets from the user-supplied slave.size -- validated against the VME address space (up to VME_A32_MAX = 4 GiB), not against PCI_BUF_SIZE. When the window exceeds 128 KiB, a write()/read() copies past the kern_buf allocation. Clamp count against size_buf in both helpers, with an early return when *ppos is already at/after the buffer end. *ppos is >= 0 here (the caller rejects negative offsets), so size_buf - *ppos cannot wrap. This mirrors the existing clamp in the MASTER-path helpers resource_to_user() / resource_from_user(), and matches the read()/write() convention of a short transfer at end-of-buffer. Found by static analysis (CodeQL taint tracking + CBMC bounded model checking) and confirmed dynamically under KASAN with the vme_fake bridge: BUG: KASAN: slab-out-of-bounds in _copy_from_user+0x2d/0x80 Write of size 262144 at addr ffff888004100000 by task trigger/68 _copy_from_user+0x2d/0x80 vme_user_write+0x13e/0x240 [vme_user] vfs_write+0x1b8/0x7a0 ksys_write+0xb8/0x150

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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