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CVE-2026-64539NVD status: Analyzed

Linux: Stack-based Buffer Overflow

Published Updated By the CyberSecBulletin desk

CVE-2026-64539 is a high-severity stack-based buffer overflow 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 0f0b6232af56441d0a2dcb173cc4f8d8aab39014, 9174992ee1045c9c96e53eecda64f49dd7e8fbba, 09301f1fdf2aef8cce34d0c4650c30e7edb1ced9 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 0f0b6232af56441d0a2dcb173cc4f8d8aab39014 or 9174992ee1045c9c96e53eecda64f49dd7e8fbba or 09301f1fdf2aef8cce34d0c4650c30e7edb1ced9 or f1b4df9c260c51726da2e86e19322825fddeefd0, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.1.178 or 6.6.160 or 6.12.97 or 6.18.40, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxb44133ff03be30b55f23036e62f403a3f7784fce up to, but not including, 0f0b6232af56441d0a2dcb173cc4f8d8aab39014; b44133ff03be30b55f23036e62f403a3f7784fce up to, but not including, 9174992ee1045c9c96e53eecda64f49dd7e8fbba; b44133ff03be30b55f23036e62f403a3f7784fce up to, but not including, 09301f1fdf2aef8cce34d0c4650c30e7edb1ced9; b44133ff03be30b55f23036e62f403a3f7784fce up to, but not including, f1b4df9c260c51726da2e86e19322825fddeefd0; b44133ff03be30b55f23036e62f403a3f7784fce up to, but not including, 57077eeb586c42f124bc09e018449362223067b3; b44133ff03be30b55f23036e62f403a3f7784fce up to, but not including, 6f5fb689fdf80bdd143f22a502f9eb1f3c85e286; 4.10f0b6232af56441d0a2dcb173cc4f8d8aab39014, 9174992ee1045c9c96e53eecda64f49dd7e8fbba, 09301f1fdf2aef8cce34d0c4650c30e7edb1ced9, f1b4df9c260c51726da2e86e19322825fddeefd0, 57077eeb586c42f124bc09e018449362223067b3, 6f5fb689fdf80bdd143f22a502f9eb1f3c85e286
LinuxLinux Kernel4.1 up to, but not including, 6.1.178; 6.2 up to, but not including, 6.6.160; 6.7 up to, but not including, 6.12.97; 6.13 up to, but not including, 6.18.40; 6.19 up to, but not including, 7.1.56.1.178, 6.6.160, 6.12.97, 6.18.40, 7.1.5

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: eir: Fix stack OOB write when prepending the Flags AD eir_create_adv_data() builds the advertising data into a fixed-size buffer ("size", 31 for the legacy path). It may prepend a 3-byte "Flags" AD structure (LE_AD_NO_BREDR on an LE-only controller) and then copies the per-instance data without checking that it still fits: memcpy(ptr, adv->adv_data, adv->adv_data_len); tlv_data_max_len() only reserves those 3 bytes when the user-supplied flags carry a managed-flags bit, so an instance added with flags == 0 is accepted with adv_data_len up to the full buffer. At advertise time the flags are still prepended, and the memcpy() writes 3 + adv_data_len bytes into the size-byte buffer: BUG: KASAN: stack-out-of-bounds in eir_create_adv_data (net/bluetooth/eir.c:301) Write of size 31 at addr ffff88800a547bdc by task kworker/u9:0/65 Workqueue: hci0 hci_cmd_sync_work __asan_memcpy (mm/kasan/shadow.c:106) eir_create_adv_data (net/bluetooth/eir.c:301) hci_update_adv_data_sync (net/bluetooth/hci_sync.c:1310) hci_schedule_adv_instance_sync (net/bluetooth/hci_sync.c:1817) hci_cmd_sync_work (net/bluetooth/hci_sync.c:332) This frame has 1 object: [32, 64) 'cp' The "Flags" structure is added by the kernel, not requested by userspace, so only prepend it when it fits together with the instance advertising data; when there is no room for both, drop the flags rather than the user-provided data. Reachable by a local user with CAP_NET_ADMIN owning an LE-only controller on the legacy advertising path.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Stack-based Buffer Overflow

The product writes past the end of a buffer that was allocated on the stack.

How developers prevent this class of flaw

  • 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.
  • Use an abstraction library to abstract away risky APIs. Not a complete solution.
  • Implement and perform bounds checking on input.

More Stack-based Buffer Overflow vulnerabilities (CWE-121)

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 Stack-based Buffer Overflow vulnerabilities

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