CVE-2026-72389
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk6th percentile - higher than 6% of all known CVEs
Summary
A use-after-free vulnerability was found in the Linux kernel's bridge subsystem related to STP. Missing IFF_UP check in br_topology_change_detection() allows arming the topology change timer while the bridge is administratively down, leading to use-after-free when the bridge is deleted.
Risk Assessment
An attacker could cause a kernel crash or potentially execute arbitrary code in the kernel, threatening system integrity and availability.
Recommendation
Apply a Linux kernel update containing the fix that adds the missing check and synchronously shuts down STP timers when the bridge is deleted.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: bridge: stp: Fix a potential use-after-free when deleting a bridge The three STP timers are not supposed to be armed while the bridge is administratively down. They are synchronously deactivated when the bridge is put administratively down and the various call sites check for 'IFF_UP' before arming them. This check is missing from br_topology_change_detection() and it is possible to engineer a situation in which the topology change timer is armed while the bridge is administratively down, resulting in a use-after-free [1] when the bridge is deleted. Fix by adding the missing check and for good measures synchronously shutdown the three timers when the bridge is deleted. [1] ODEBUG: free active (active state 0) object: ffff88811662b9b0 object type: timer_list hint: br_topology_change_timer_expired (net/bridge/br_stp_timer.c:120) WARNING: lib/debugobjects.c:629 at debug_print_object+0x1bc/0x450, CPU#9: ip/359