CVE Catalog

CVE-2026-89569

HighCVSS 8.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.31%

24th percentile - higher than 24% of all known CVEs

Summary

A use-after-free vulnerability exists in the Linux kernel's rfcomm_security_cfm() function in the Bluetooth RFCOMM subsystem. The function walks the session and DLC lists without holding rfcomm_mutex, allowing the krfcommd thread to concurrently free the same session and its DLCs. This results in a read of freed memory (KASAN: slab-use-after-free).

Risk Assessment

The vulnerability can cause a kernel panic or potentially allow code execution in kernel context, threatening system confidentiality, integrity, and availability. It affects systems with active Bluetooth RFCOMM.

Recommendation

Update the Linux kernel to a version containing the fix that serializes rfcomm_security_cfm() handling with rfcomm_mutex. If updating is not possible, consider disabling Bluetooth or restricting RFCOMM usage.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: RFCOMM: serialize security confirmation handling rfcomm_security_cfm() looks up a session on session_list and then walks its DLC list without holding rfcomm_mutex. Since RFCOMM session teardown uses rfcomm_mutex, krfcommd can close and free the same session and DLCs concurrently: hci_rx_work krfcommd ----------- --------- rfcomm_session_get() rfcomm_lock() rfcomm_session_close() rfcomm_dlc_unlink() rfcomm_session_del() kfree(s) rfcomm_unlock() walk s->dlcs The callback can then read a freed session list head and touch freed DLCs while updating their flags or timers. Serialize the session lookup and DLC traversal in rfcomm_security_cfm() with rfcomm_mutex. This matches the existing RFCOMM session lifetime rules and prevents concurrent rfcomm_session_del() / rfcomm_dlc_unlink() from tearing the objects down while the callback is using them. KASAN reported: BUG: KASAN: slab-use-after-free in rfcomm_security_cfm+0x41c/0x440 Read of size 8 at addr ffff888111fb3960 by task kworker/u17:1/89 Workqueue: hci0 hci_rx_work Call Trace: rfcomm_security_cfm+0x41c/0x440 hci_encrypt_cfm+0x139/0x590 hci_encrypt_change_evt+0x37b/0xc40 hci_event_packet+0x71b/0xb20 hci_rx_work+0x293/0x730 Allocated by task 69: rfcomm_session_add+0x9e/0x2f0 rfcomm_run+0x44b/0x41e0 Freed by task 69: kfree+0x131/0x3c0 rfcomm_session_del+0x188/0x220 rfcomm_run+0x1985/0x41e0

Vulnerability data from NVD (NIST) · CISA KEV · EPSS