CVE-2026-68169

mptcp: pm: userspace: fix use-after-free in get_local_id

N/A

Published: August 10, 2026 at 11:59 AM UTC

Updated: August 23, 2026 at 01:17 PM UTC

1 product affected across 1 vendorLinux Kernel

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Severity

N/A

Exploit prediction

EPSS 0.2%

Description

In the Linux kernel, the following vulnerability has been resolved: mptcp: pm: userspace: fix use-after-free in get_local_id In mptcp_pm_userspace_get_local_id(), the address entry is looked up under spinlock, but its id is read after dropping the lock. A concurrent deletion can free the entry between the unlock and the read, leading to UAF. The race window is narrow. It was reproduced only with a locally constructed stress test that repeatedly overlaps an MP_JOIN SYN with a MPTCP_PM_CMD_SUBFLOW_DESTROY request. However, the KASAN report below confirms that the race is reachable: [ 666.319376] BUG: KASAN: slab-use-after-free in mptcp_userspace_pm_get_local_id+0x1dc/0x1f0 [ 666.319386] Read of size 1 at addr ffff888124845610 by task swapper/0/0 ... [ 666.319401] Call Trace: [ 666.319405] <IRQ> [ 666.319408] dump_stack_lvl+0x53/0x70 [ 666.319412] print_address_description.constprop.0+0x2c/0x3b0 [ 666.319418] print_report+0xbe/0x2b0 [ 666.319421] ? mptcp_userspace_pm_get_local_id+0x1dc/0x1f0 [ 666.319423] kasan_report+0xce/0x100 [ 666.319426] ? mptcp_userspace_pm_get_local_id+0x1dc/0x1f0 [ 666.319429] mptcp_userspace_pm_get_local_id+0x1dc/0x1f0 [ 666.319433] mptcp_pm_get_local_id+0x371/0x440 ... [ 666.319821] Allocated by task 45539: [ 666.319844] kasan_save_stack+0x33/0x60 [ 666.319855] kasan_save_track+0x14/0x30 [ 666.319858] __kasan_kmalloc+0x8f/0xa0 [ 666.319863] __kmalloc_noprof+0x1e7/0x520 [ 666.319867] sock_kmalloc+0xdf/0x130 [ 666.319885] sock_kmemdup+0x1b/0x40 [ 666.319888] mptcp_userspace_pm_append_new_local_addr+0x261/0x500 [ 666.319910] mptcp_pm_nl_announce_doit+0x16a/0x610 ... [ 666.319967] Freed by task 45560: [ 666.319988] kasan_save_stack+0x33/0x60 [ 666.319991] kasan_save_track+0x14/0x30 [ 666.319994] kasan_save_free_info+0x3b/0x60 [ 666.319998] __kasan_slab_free+0x43/0x70 [ 666.320000] kfree+0x166/0x440 [ 666.320003] sock_kfree_s+0x1d/0x50 [ 666.320007] mptcp_userspace_pm_delete_local_addr.isra.0+0x157/0x200 [ 666.320011] mptcp_pm_nl_subflow_destroy_doit+0x51d/0xea0 Fix by copying the id into a local variable while still holding the lock, and use -1 as a "not found" sentinel.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Linux Kernel · Linux

95%

v ≥ 6.7.66.1.79 ≤ v < 6.1.1846.6.18 ≤ v < 6.6.1516.7.6 ≤ v < 6.86.8 ≤ v < 6.12.1036.8 ≤ v < 6.18.426.8 ≤ v < 7.1.66.8 ≤ v < 7.25a3ad289eb604216dcaa3646de36cb8624a06.1.79 6.6.18 6.7.6 6.8e373bfc8ec3d6496ec7e11dd7f4d087a44b1009aed34dfa19ddbd1e4c85a73636f8cba0211025ea4f012d796a6de662692159c539689e47e662853a8

Vendor states this is fixed in 31ce5af66891f79998fb2e8b8df08e3c98fd72e3 (fixed)

Vendor states this is fixed in 40dde4b5d98279471a70e5c8bb713182738c00d9 (fixed)

Vendor states this is fixed in 8ce48d2879aafc0e7a6f8bfc3613c0ba979ec6f5 (fixed)

Vendor states this is fixed in 9bc6d5e4ca9f3cbb41d43400b3a31cb0403796c9 (fixed)

Vendor states this is fixed in d2c3760b45f2f481a4dd4c5adef4a29dfabd948f (fixed)

Vendor states this is fixed in d64f6c02495f3fad674038cfa7ec049671b59e7b (fixed)

Vendor states this is fixed in 6.1.184 (unaffected)

Vendor states this is fixed in 6.12.103 (unaffected)

Vendor states this is fixed in 6.18.42 (unaffected)

Vendor states this is fixed in 6.6.151 (unaffected)

Vendor states this is fixed in 6.8 (unaffected)

Vendor states this is fixed in 7.1.6 (unaffected)