CVE-2026-74536

Received Received - Intake

Bluetooth ISO Socket Reference Leak in Linux Kernel

Publication date: 2026-08-15

Last updated on: 2026-08-17

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: ISO: fix leaking sk after socket release iso_sock_kill() tests !sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket || sock_flag(sk, SOCK_DEAD) for early return, but this is always true since sock_orphan(sk) sets SOCK_DEAD, so the sk reference released by socket always leaks, iso_sock_destruct is never called. The socket reference also leaks when __iso_sock_close() does not set SOCK_ZAPPED, since iso_conn_del() does not call iso_sock_kill() after zapping. Fix by replacing SOCK_DEAD by BT_SK_KILLED flag that is not used for something else, and lock_sock to ensure iso_sock_kill() puts sk only after socket release only once. Release and iso_conn_del may run concurrently. Call iso_sock_kill() from iso_conn_del() to clean sk up after zapping. Remove call to iso_sock_kill() from iso_sock_close(), as it's generally no-op there.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-15

Last Modified

2026-08-17

Generated

2026-09-04

AI Q&A

2026-08-15

EPSS Evaluated

2026-09-03

NVD

CVE-2026-74536

EUVD

EUVD-2026-59729

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 vulnerability in the Linux kernel involves a memory leak in Bluetooth ISO sockets. When a socket is released, the kernel fails to properly clean up the associated data structure (sk), causing a reference leak. The issue occurs because flags like SOCK_DEAD are set incorrectly, preventing the cleanup function (iso_sock_destruct) from running. A new flag (BT_SK_KILLED) and locking mechanism are introduced to fix this.

Detection Guidance

This vulnerability is specific to the Linux kernel's Bluetooth ISO socket handling. Detection requires checking for kernel versions affected by the flaw and inspecting Bluetooth socket states. Commands like 'uname -a' to check kernel version and 'ss -tulnp | grep bluetooth' to inspect Bluetooth sockets may help identify potential exposure.

Impact Analysis

This vulnerability could lead to resource exhaustion on systems using Bluetooth ISO sockets. Over time, unpatched systems may experience degraded performance or crashes due to accumulated leaked memory. Attackers might exploit this to cause denial-of-service conditions on affected devices.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards. It is a memory leak issue in the Linux kernel's Bluetooth ISO socket handling, which could lead to resource exhaustion but does not involve data breaches or unauthorized access to sensitive information.

Mitigation Strategies

Apply the latest kernel updates from your Linux distribution to patch the Bluetooth ISO socket handling flaw. Restart affected services or reboot the system after applying updates. Monitor for unusual Bluetooth activity or socket leaks as indicators of exploitation.

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