CVE-2026-68188

Received Received - Intake

Use-After-Free in Linux Kernel Bluetooth RFCOMM

Publication date: 2026-08-10

Last updated on: 2026-08-19

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: RFCOMM: Fix session UAF in set_termios rfcomm_tty_set_termios() tests dlc->session without rfcomm_mutex and later passes the pointer to rfcomm_send_rpn(). The latter dereferences both session->initiator and session->sock. Meanwhile, krfcommd can unlink the DLC and free the session while holding rfcomm_mutex. The race can proceed as follows: TTY ioctl task krfcommd -------------- -------- load dlc->session enter rfcomm_send_rpn() lock rfcomm_mutex clear dlc->session free session unlock rfcomm_mutex read session->initiator KASAN reported: BUG: KASAN: slab-use-after-free in rfcomm_send_rpn+0x297/0x2a0 Read of size 4 at addr ffff88810012a850 by task poc/92 Call Trace: rfcomm_send_rpn+0x297/0x2a0 rfcomm_tty_set_termios+0x50d/0x850 tty_set_termios+0x596/0x950 set_termios+0x46a/0x6e0 tty_mode_ioctl+0x152/0xbd0 tty_ioctl+0x915/0x1240 __x64_sys_ioctl+0x134/0x1c0 Allocated by task 92: rfcomm_session_add+0x9e/0x2e0 rfcomm_dlc_open+0x8b1/0xe00 rfcomm_dev_activate+0x85/0x1a0 rfcomm_tty_open+0x90/0x280 Freed by task 68: kfree+0x131/0x3c0 rfcomm_session_del+0x119/0x180 rfcomm_run+0x737/0x4710 Add rfcomm_dlc_send_rpn(), which holds rfcomm_mutex while it verifies that the DLC is still attached and sends the RPN frame. Have the TTY path use the helper and drop its unlocked session check. This keeps the session valid through both the frame construction and socket send.

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Meta Information

Published

2026-08-10

Last Modified

2026-08-19

Generated

2026-08-30

AI Q&A

2026-08-10

EPSS Evaluated

2026-08-29

NVD

CVE-2026-68188

EUVD

EUVD-2026-55289

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This is a use-after-free (UAF) vulnerability in the Linux kernel's Bluetooth RFCOMM subsystem. It occurs when a session pointer is accessed without proper locking, leading to a race condition where the session is freed while still being used. The flaw is in rfcomm_tty_set_termios() which checks dlc->session without holding rfcomm_mutex before passing it to rfcomm_send_rpn(), which then dereferences freed memory.

Detection Guidance

This vulnerability is specific to the Linux kernel's Bluetooth RFCOMM subsystem and may not have direct network detection methods. However, you can check for kernel logs indicating use-after-free errors in Bluetooth components. Look for messages like 'BUG: KASAN: slab-use-after-free in rfcomm_send_rpn' in system logs using commands like 'dmesg | grep -i kasan' or 'journalctl -k | grep -i kasan'.

Impact Analysis

This vulnerability could allow an attacker to cause a kernel crash or execute arbitrary code with kernel privileges by exploiting the race condition. It may lead to denial-of-service conditions or potential privilege escalation on affected systems using Bluetooth RFCOMM functionality.

Compliance Impact

This vulnerability is a use-after-free flaw in the Linux kernel's Bluetooth RFCOMM subsystem. It does not directly impact compliance with standards like GDPR or HIPAA, as those focus on data protection and privacy controls rather than kernel-level memory safety issues.

Mitigation Strategies

Update your Linux kernel to a version that includes the fix for this vulnerability. Since the issue is resolved in the kernel, applying the latest stable kernel update will mitigate the risk. Check your distribution's security advisories for the specific kernel version containing the patch.

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