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A use-after-free flaw in the Linux kernel Bluetooth HCI SCO subsystem, tracked as CVE-2021-3640, can allow a local privileged attacker to crash a host or escalate privileges. The vulnerability stems from a race involving sco_sock_sendmsg() and sco_conn_del(); it can be triggered through UFFDIO_REGISTER or a comparable mechanism by an attacker holding CAP_NET_ADMIN in the initial user namespace.
Red Hat assigned the issue a Moderate severity rating with a CVSS v3.1 score of 6.7 and classified it as CWE-825, expired pointer dereference. Fixed kernel and kernel-rt packages were released for Red Hat Enterprise Linux 8 and 9, with further fixes for RHEL 8.6 EUS and Red Hat Virtualization; RHEL 6 is unaffected, while out-of-support RHEL 7 kernel variants should be treated as potentially affected.
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3 events from the most recent confirmed update back to the earliest known activity.
Red Hat issued RHSA-2022:7444 for the RHEL 8 kernel-rt and RHSA-2022:7683 for the RHEL 8 kernel, addressing the Bluetooth SCO use-after-free vulnerability CVE-2021-3640.
Red Hat issued RHSA-2024:0724 to fix CVE-2021-3640 in the RHEL 8.6 Extended Update Support kernel and Red Hat Virtualization 4 for RHEL 8.
Red Hat issued RHSA-2022:8267 for the RHEL 9 kernel and RHSA-2022:7933 for the RHEL 9 kernel-rt to fix CVE-2021-3640.
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A use-after-free flaw in the Linux kernel's Bluetooth SCO implementation, tracked as **CVE-2026-31408**, was fixed after maintainers found that `sco_recv_frame()` could access a socket after it had been freed during a concurrent `close()`. The bug stems from reading `conn->sk` while holding `sco_conn_lock()` and then releasing the lock before safely retaining a socket reference, creating a race that can lead to memory corruption or a denial of service. Upstream records say the vulnerable code path existed since Linux `2.6.12`, and the fix adds `sco_sock_hold()` before unlocking along with `sock_put()` on all exit paths. The Linux kernel CVE team published fixes across multiple stable branches, including `6.6.131`, `6.12.80`, `6.18.21`, `6.19.11`, and `7.0-rc6`, and advised users to move to the latest stable kernel rather than cherry-picking patches. Red Hat rated the issue **Moderate** for its products, assigned a CVSS v3 score of `7.0`, and said updated kernel packages were released for multiple Red Hat Enterprise Linux lines, including **RHEL 8, 9, and 10** and related support variants; upstream CVE scoring lists the flaw at `8.8` under adjacent-network Bluetooth attack conditions.
Aug 25, 2026
**CVE-2023-51779** is a use-after-free flaw in the Linux kernel Bluetooth subsystem caused by a race between `bt_sock_recvmsg()` and `bt_sock_ioctl()` over a socket buffer. A local low-privileged user could trigger a denial of service and may potentially execute code; Red Hat rates the issue Moderate, with CVSS 7.0, while noting exploitation is difficult and local privilege escalation has not been confirmed. The upstream fix is available in commit `2e07e8348ea454615e268222ae3fc240421be768`, and Fedora addressed the issue in its 6.6.9 stable kernel updates. Red Hat released fixes for affected RHEL 8 and 9 streams, including RHSA-2024:3859 for supported RHEL 8.6 extended-support variants, which provides kernel `4.18.0-372.107.1.el8_6`; affected systems require a reboot after installation. RHEL 6 is outside support scope and should be considered affected.
Aug 26, 2026
**CVE-2022-3564** is a use-after-free flaw in the Linux kernel Bluetooth L2CAP implementation, in `l2cap_reassemble_sdu()` within `net/bluetooth/l2cap_core.c`. A local user or an attacker able to establish a Bluetooth connection can use two malicious L2CAP packet flows to trigger a race condition, potentially crashing the host or escalating privileges. Red Hat rates the issue CVSS 7.1; exploitation requires low privileges and winning a narrow timing window, and no practical exploit was known. The upstream fix is available in commit `89f9f3cb86b1c63badaf392a83dd661d56cc50b1`, with Fedora remediating it in Linux 6.0.8 stable updates and Red Hat issuing fixes for affected RHEL 7, 8, and 9 channels, including RHSA-2023:4150 and RHSA-2023:4151. Organizations unable to patch should disable Bluetooth at the hardware or BIOS level, or block Bluetooth kernel modules such as `bnep`, `bluetooth`, and `btusb` and disable the Bluetooth service.
Aug 26, 2026