CVE-2026-64539: Linux kernel · Stack-based Buffer Overflow
Affects Linux kernelSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 27 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
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
- git.kernel.org/stable/c/0f0b6232af56441d0a2dcb173cc4f8d8aab39014 (opens in a new tab)
- git.kernel.org/stable/c/9174992ee1045c9c96e53eecda64f49dd7e8fbba (opens in a new tab)
- git.kernel.org/stable/c/09301f1fdf2aef8cce34d0c4650c30e7edb1ced9 (opens in a new tab)
- git.kernel.org/stable/c/f1b4df9c260c51726da2e86e19322825fddeefd0 (opens in a new tab)
- git.kernel.org/stable/c/57077eeb586c42f124bc09e018449362223067b3 (opens in a new tab)
- git.kernel.org/stable/c/6f5fb689fdf80bdd143f22a502f9eb1f3c85e286 (opens in a new tab)