CyberSecBulletin
CVE-2026-53209NVD status: Modified

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-53209 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 10b0e832cc05d7aef4b92bed912cbd4a395d0862, 1338ee049a8910ba6c9cee963920e978e6893c7d, 02f50e8bb69f9b22516163a09922f5537d3b12d1 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 10b0e832cc05d7aef4b92bed912cbd4a395d0862 or 1338ee049a8910ba6c9cee963920e978e6893c7d or 02f50e8bb69f9b22516163a09922f5537d3b12d1 or dafc9f57140e66a10945127aa7433c3d715dc253, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.1.176 or 6.6.143 or 6.12.94 or 6.16, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux63f365eb4d1668a04070151b555d55a07ede8d4b up to, but not including, 10b0e832cc05d7aef4b92bed912cbd4a395d0862; c621211b308816889f0a3246de448bfcef8ab3ab up to, but not including, 1338ee049a8910ba6c9cee963920e978e6893c7d; 907ef6e12fb558a0763e894311eb245a94c192dd up to, but not including, 02f50e8bb69f9b22516163a09922f5537d3b12d1; 5725bc608252050ed8a4d47d59225b7dd73474c8 up to, but not including, dafc9f57140e66a10945127aa7433c3d715dc253; 5725bc608252050ed8a4d47d59225b7dd73474c8 up to, but not including, cdd8bbdbee763fdf5bf343e6f7d4e79347739f62; 5725bc608252050ed8a4d47d59225b7dd73474c8 up to, but not including, 5c65b96b549ea2dcfde497436bf9e048deb87758; 15da883c010cbc2a84aec1738b6ad6ee477846de; 6.1.142 up to, but not including, 6.1.176; and 4 more ranges10b0e832cc05d7aef4b92bed912cbd4a395d0862, 1338ee049a8910ba6c9cee963920e978e6893c7d, 02f50e8bb69f9b22516163a09922f5537d3b12d1, dafc9f57140e66a10945127aa7433c3d715dc253, cdd8bbdbee763fdf5bf343e6f7d4e79347739f62, 5c65b96b549ea2dcfde497436bf9e048deb87758
LinuxLinux Kernel6.1.142 up to, but not including, 6.1.176; 6.6.94 up to, but not including, 6.6.143; 6.12.34 up to, but not including, 6.12.94; 6.15.3 up to, but not including, 6.16; 6.16.1 up to, but not including, 6.18.36; 6.19 up to, but not including, 7.0.13; 6.16; 7.16.1.176, 6.6.143, 6.12.94, 6.16, 6.18.36, 7.0.13

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: Bluetooth: hci_sync: reject oversized Broadcast Announcement prepend Existing advertising instances can already hold the maximum extended advertising payload. When hci_adv_bcast_annoucement() prepends the Broadcast Announcement service data to that payload, the combined data may no longer fit in the temporary buffer used to rebuild the advertising data. Reject that case before copying the existing payload and report the failure through the device log. This keeps the existing advertising data intact and avoids overrunning the temporary buffer.

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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