# CVE-2026-98738: Bluetooth: Serialize SMP remote OOB data access

> A race condition in the Linux kernel Bluetooth SMP implementation allows attackers to trigger a use-after-free, potentially leading to code execution or system crashes.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-108674, BELL-CVE-2026-98738, DEBIAN-CVE-2026-98738, GHSA-pp83-8gx8-qvjg, UBUNTU-CVE-2026-98738

## What is CVE-2026-98738?

CVE-2026-98738 is an use after free vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: Serialize SMP remote OOB data access

build_pairing_cmd() looks up remote OOB data and copies its contents
without holding hdev->lock, which serializes the list's writers. After
SMP finds an entry, a concurrent management Remove Remote OOB Data
command can unlink and free it before SMP reads its present flag or
copies its random and confirmation values. Removal can also invalidate
an entry while the lookup is still traversing the list.

KASAN reported:

  BUG: KASAN: slab-use-after-free in build_pairing_cmd+0x948/0x9b0
  Call Trace:
   build_pairing_cmd+0x948/0x9b0
   smp_recv_cb+0x459f/0x8110
   l2cap_recv_frame+0xf14/0x9190
   l2cap_recv_acldata+0xa64/0xd40
   hci_rx_work+0x4ca/0x730

  Allocated by task 87:
   hci_add_remote_oob_data+0x11d/0x530
   add_remote_oob_data+0x282/0x400
   hci_sock_sendmsg+0x1033/0x1ea0

  Freed by task 93:
   hci_remote_oob_data_clear+0x108/0x1c0
   remove_remote_oob_data+0x198/0x220
   hci_sock_sendmsg+0x1033/0x1ea0

Taking hdev->lock in build_pairing_cmd() would recurse for callers that
already hold it and invert the device-to-L2CAP lock order on the receive
path. Add a per-device remote_oob_lock instead, held across the SMP
lookup and copies and by the add, remove and clear helpers. Cover
initialization and in-place updates as well, so SMP cannot read partially
initialized or updated OOB values. Release the mutex on allocation
failure, preserving the existing error return.

The new critical sections acquire no device, connection or channel locks.
Writers retain their existing hdev->lock protection, which continues to
serialize the other readers without changing their locking or behavior.

## Which versions are affected by CVE-2026-98738?


## How do I fix CVE-2026-98738?

Apply the vendor's patch.

## Is CVE-2026-98738 being exploited?

There is no known exploitation of CVE-2026-98738 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98738 and fix it if it is affected.

What it is: CVE-2026-98738 is an use after free vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-98738 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-98738/ (Markdown: https://insights.sbomify.com/CVE-2026-98738/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98738
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98738
- OSV: https://osv.dev/vulnerability/CVE-2026-98738

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98738/
Summaries are generated and may contain mistakes; the official description above is the record.