CyberSecBulletin
CVE-2026-46209NVD status: Modified

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-46209 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 11427ad6c9f0def5ce567982b785da3191946430, adfc5ba4ef4dd2bca5969f40e8fc7b41fb3902ad, 22922f7dae74409fc4bf0f1142710cb6b8ce8cc2 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 11427ad6c9f0def5ce567982b785da3191946430 or adfc5ba4ef4dd2bca5969f40e8fc7b41fb3902ad or 22922f7dae74409fc4bf0f1142710cb6b8ce8cc2 or 6b992591e04f2cce813bcf239b354f375bbf84d3, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.258 or 5.15.209 or 6.1.175 or 6.6.140, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux4c3dbb2c312c9fafbac30d98c523b8b1f3455d78 up to, but not including, 11427ad6c9f0def5ce567982b785da3191946430; 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78 up to, but not including, adfc5ba4ef4dd2bca5969f40e8fc7b41fb3902ad; 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78 up to, but not including, 22922f7dae74409fc4bf0f1142710cb6b8ce8cc2; 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78 up to, but not including, 6b992591e04f2cce813bcf239b354f375bbf84d3; 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78 up to, but not including, 1da4ab7189f1064b3b712b388772c008b4d82580; 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78 up to, but not including, 1a17ea9861e89585361caa8bc231bd22dc6dbe7d; 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78 up to, but not including, c5fc49d8470c5ebf3b41607600f277158f159950; 4c3dbb2c312c9fafbac30d98c523b8b1f3455d78 up to, but not including, 3d4c2268bd7243c3780fe32bf24ff876da272acf; and 1 more ranges11427ad6c9f0def5ce567982b785da3191946430, adfc5ba4ef4dd2bca5969f40e8fc7b41fb3902ad, 22922f7dae74409fc4bf0f1142710cb6b8ce8cc2, 6b992591e04f2cce813bcf239b354f375bbf84d3, 1da4ab7189f1064b3b712b388772c008b4d82580, 1a17ea9861e89585361caa8bc231bd22dc6dbe7d
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystemall versionsNot stated
LinuxLinux Kernel4.14 up to, but not including, 5.10.258; 5.11 up to, but not including, 5.15.209; 5.16 up to, but not including, 6.1.175; 6.2 up to, but not including, 6.6.140; 6.7 up to, but not including, 6.12.90; 6.13 up to, but not including, 6.18.32; 6.19 up to, but not including, 7.0.9; 7.15.10.258, 5.15.209, 6.1.175, 6.6.140, 6.12.90, 6.18.32

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: drm/gem: Fix inconsistent plane dimension calculation in drm_gem_fb_init_with_funcs() drm_gem_fb_init_with_funcs() computes sub-sampled plane dimensions using plain integer division: unsigned int width = mode_cmd->width / (i ? info->hsub : 1); unsigned int height = mode_cmd->height / (i ? info->vsub : 1); However, the ioctl-level framebuffer_check() in drm_framebuffer.c uses drm_format_info_plane_width/height() which round up dimensions via DIV_ROUND_UP(). This inconsistency corrupts the subsequent GEM object size check for certain pixel format and dimension combinations. For example, with NV12 (vsub=2) and a 1-pixel-tall framebuffer the GEM size validation path sees height=0 instead of height=1. The expression (height - 1) then wraps to UINT_MAX as an unsigned int, causing min_size to overflow and wrap back to a small value. A tiny GEM object therefore passes the size guard, yet when the GPU accesses the chroma plane it will read or write memory beyond the object's bounds. Fix by replacing the open-coded divisions with drm_format_info_plane_width() and drm_format_info_plane_height(), which use DIV_ROUND_UP() and match the calculation already used in framebuffer_check().

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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