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VulnerabilityPublished Updated

CVE-2026-64539: Linux kernel · Stack-based Buffer Overflow

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in f1b4df9c260c51726da2e86e19322825fddeefd0 : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:07 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in f1b4df9c260c51726da2e86e19322825fddeefd0, 9174992ee1045c9c96e53eecda64f49dd7e8fbba, 57077eeb586c42f124bc09e018449362223067b3 +3
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ b44133ff03be30b55f23036e62f403a3f7784fce, < f1b4df9c260c51726da2e86e19322825fddeefd0
Fixed in
  • f1b4df9c260c51726da2e86e19322825fddeefd0
LinuxLinuxAffected
  • ≥ b44133ff03be30b55f23036e62f403a3f7784fce, < 9174992ee1045c9c96e53eecda64f49dd7e8fbba
Fixed in
  • 9174992ee1045c9c96e53eecda64f49dd7e8fbba
LinuxLinuxAffected
  • ≥ b44133ff03be30b55f23036e62f403a3f7784fce, < 57077eeb586c42f124bc09e018449362223067b3
Fixed in
  • 57077eeb586c42f124bc09e018449362223067b3
LinuxLinuxAffected
  • ≥ b44133ff03be30b55f23036e62f403a3f7784fce, < 09301f1fdf2aef8cce34d0c4650c30e7edb1ced9
Fixed in
  • 09301f1fdf2aef8cce34d0c4650c30e7edb1ced9
LinuxLinuxAffected
  • ≥ b44133ff03be30b55f23036e62f403a3f7784fce, < 6f5fb689fdf80bdd143f22a502f9eb1f3c85e286
Fixed in
  • 6f5fb689fdf80bdd143f22a502f9eb1f3c85e286
LinuxLinuxAffected
  • ≥ b44133ff03be30b55f23036e62f403a3f7784fce, < 0f0b6232af56441d0a2dcb173cc4f8d8aab39014
Fixed in
  • 0f0b6232af56441d0a2dcb173cc4f8d8aab39014

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.

References

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