Patch Forecast
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CVE-2026-64539

Canonical Ubuntu Linux: stack buffer overflow

Risk score
62/100
CVSS
7.8 v3.1
Published
27 Jul 2026

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What to know

What it is
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 co…
Affected
Canonical Ubuntu Linux
Fix
Apply the vendor's security update; see the linked advisory.
Exploitation
No known exploitation

Story map

Story map: Canonical Ubuntu LinuxTHE FLAWSTHE FIXCVE-2026-64539Stack buffer overflowCVSS 7.8CVE-2026-93479Heap buffer overflow can leadto remote code executionCVSS 8.1 · EPSS 1%CVE-2026-15176Heap buffer overflow can leadto remote code executionCVSS 8.1 · EPSS 1%CVE-2026-97205NGINX Plus and NGINX OpenSource have a vulnerability inthe ngx_http_core_module…CVSS 8.1 · EPSS 1%FixCheck the linked advisory forthe concrete fix.Who is exposed{'products': ['NGINX Plus','NGINX Open Source'],'packages': [], 'versions': []}RED · ACT TODAYCanonical UbuntuLinuxA vulnerability exists in NGINXPlus and NGINX Open Sourcewhen a map directive uses regexmatching and the root directiveor access log format referencesthe map's regex capturevariables before referencing…Where it standsNo known exploitationHOW IT UNFOLDEDOfficial record on the left, the press on the right, oldest first.26 Oct · Ubuntu security noticesUSN-8955-1: nginx vulnerabilities5 Nov · Ubuntu security noticesUSN-8955-2: nginx vulnerabilities6 Nov · Ubuntu security noticesUSN-9003-1: Linux kernel (NVIDIA) vulnerabilitiesCONNECTS TOSame weaknessStack buffer overflow (CWE-121)271 other warnings in 30 days →Same productEarlier Canonical Ubuntu Linux warnings163 in the last 90 days →
Story map: the flaws, the fix, how it unfolded and what it connects to. Boxes link to the record or article.

At a glance

Canonical Ubuntu Linux: Red, act today. A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and the root directive or access log format references the map's regex capture variables before referencing the map output variable. An unauthenticated attacker can exploit this vulnerability by sending crafted HTTP requests, causing a heap buffer overflow in the NGINX worker process leading to a restart, or potential…

The flaws

  • CVE-2026-64539: Stack buffer overflow (CVSS 7.8)
  • CVE-2026-93479: Heap buffer overflow can lead to remote code execution (CVSS 8.1 · EPSS 1%)
  • CVE-2026-15176: Heap buffer overflow can lead to remote code execution (CVSS 8.1 · EPSS 1%)
  • CVE-2026-97205: NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_core_module module (CVSS 8.1 · EPSS 1%)

The fix

Fix: Check the linked advisory for the concrete fix.

Who is exposed: {'products': ['NGINX Plus', 'NGINX Open Source'], 'packages': [], 'versions': []}

Where it stands

  • No known exploitation

How it unfolded

  1. 26 Oct, Ubuntu security notices (official): USN-8955-1: nginx vulnerabilities
  2. 5 Nov, Ubuntu security notices (official): USN-8955-2: nginx vulnerabilities
  3. 6 Nov, Ubuntu security notices (official): USN-9003-1: Linux kernel (NVIDIA) vulnerabilities

Connects to

Why it is Amber

  • CVSS 7.8 high
  • On your watchlist: linux kernel
  • Named in a government or vendor bulletin

Government and vendor bulletins

References

Original 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.

Last activity 6 Nov 2026. Patch Forecast updates every hour.