# CVE-2026-53357: Bluetooth: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del() > A use-after-free in the Linux kernel Bluetooth subsystem allows local attackers to trigger memory corruption, potentially leading to code execution or privilege escalation. - **Severity:** High 8.0 (`CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 2 Jul 2026 - **Updated:** 19 Oct 2026 - **Also known as:** BELL-CVE-2026-53357, DEBIAN-CVE-2026-53357, GHSA-mf4h-hfv8-f4v4, ROOT-OS-DEBIAN-11-CVE-2026-53357, ROOT-OS-DEBIAN-12-CVE-2026-53357, ROOT-OS-UBUNTU-2204-CVE-2026-53357, ROOT-OS-UBUNTU-2404-CVE-2026-53357, UBUNTU-CVE-2026-53357 ## What is CVE-2026-53357? CVE-2026-53357 is a high-severity use after free vulnerability in Linux kernel, published on 2 Jul 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: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del() bt_accept_dequeue() unlinks a not-yet-accepted child from the parent accept queue and release_sock()s it before returning, so the returned sk has no caller reference and is unlocked. l2cap_sock_cleanup_listen() walks these children on listening-socket close. A concurrent HCI disconnect drives hci_rx_work -> l2cap_conn_del() which runs l2cap_chan_del() + l2cap_sock_kill() and frees the child sk and its l2cap_chan; cleanup_listen() then uses both: BUG: KASAN: slab-use-after-free in l2cap_sock_kill l2cap_sock_kill / l2cap_sock_cleanup_listen / __x64_sys_close Freed by: l2cap_conn_del -> l2cap_sock_close_cb -> l2cap_sock_kill This is distinct from the two fixes already in this area: commit e83f5e24da741 ("Bluetooth: serialize accept_q access") serialises the accept_q list/poll and takes temporary refs inside bt_accept_dequeue(), and CVE-2025-39860 serialises the userspace close()/accept() race by calling cleanup_listen() under lock_sock() in l2cap_sock_release(). Neither covers l2cap_conn_del() running from hci_rx_work, so this UAF still reproduces on current bluetooth/master. Take the reference at the source: bt_accept_dequeue() does sock_hold() while sk is still locked, before release_sock(); callers sock_put(). cleanup_listen() pins the chan with l2cap_chan_hold_unless_zero() under a brief child sk lock (serialising vs l2cap_sock_teardown_cb()), drops it before l2cap_chan_lock(), and skips a duplicate l2cap_sock_kill() on SOCK_DEAD. conn->lock is not taken here: cleanup_listen() runs under the parent sk lock and that would invert conn->lock -> chan->lock -> sk_lock (lockdep). KASAN/SMP: an unprivileged listen/close vs HCI-disconnect race produced 12 use-after-free reports per run before this change; 0, and no lockdep report, over 1600+ raced iterations after it on bluetooth/master. Weakness: CWE-416 (Use After Free) ## Which versions are affected by CVE-2026-53357? It affects 1 product. Products: Linux kernel. ## How do I fix CVE-2026-53357? Apply the vendor's patch. ## Is CVE-2026-53357 being exploited? There is no known exploitation of CVE-2026-53357 in the wild and no public exploit code. ## Other vulnerabilities in Linux kernel - [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild) - [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild) - [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild) - [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild) - [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-53357 and fix it if it is affected. What it is: CVE-2026-53357 is a high-severity use after free vulnerability in Linux kernel, published on 2 Jul 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-2026-53357 in the wild and no public exploit code. Affected product: Linux kernel. 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-2026-53357/ (Markdown: https://insights.sbomify.com/CVE-2026-53357/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53357 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53357 - OSV: https://osv.dev/vulnerability/CVE-2026-53357 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-53357/ Summaries are generated and may contain mistakes; the official description above is the record.