CVE-2026-98776

What the bug is

binderfs_binder_device_create() publishes the new dentry with d_make_persistent() and then calls simple_done_creating(), which drops the parent directory lock and the creator's dentry reference. It then calls binder_add_device() to register the device in the global binder_devices list. After simple_done_creating() releases the parent directory lock, a concurrent unlinkat() can remove the new device entry. Dropping the creator's dentry reference can then trigger binderfs_evict_inode(), freeing the device. binder_add_device() later accesses the freed object, causing UAF write. Found by a modified Syzkaller: BUG: KASAN: slab-use-after-free in hlist_add_head include/linux/list.h:1073 [inline] BUG: KASAN: slab-use-after-free in binder_add_device+0xa9/0xc0 drivers/android/binder.c:7068 Write of size 8 at addr ffff88805b340c00 by task syz.1.532/11389 CPU: 0 UID: 0 PID: 11389 Comm: syz.1.532 Not tainted 7.2.0 #4 PREEMPT(full) Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x10e/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xf7/0x600 mm/kasan/report.c:482 kasan_report+0xe4/0x120 mm/kasan/report.c:595 hlist_add_head include/linux/list.h:1073 [inline] binder_add_device+0xa9/0xc0 drivers/android/binder.c:7068 binderfs_binder_device_create.isra.0+0x724/0x990 drivers/android/binderfs.c:196 binder_ctl_ioctl+0x186/0x1b0 drivers/android/binderfs.c:241 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x116/0x800 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff9027a833d Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ff903674018 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ff902a35fa0 RCX: 00007ff9027a833d RDX: 0000200000000500 RSI: 00000000c1086201 RDI: 0000000000000004 RBP: 00007ff902850733 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ff902a36038 R14: 00007ff902a35fa0 R15: 00007ffd7166bfa0 </TASK> Allocated by task 11389: kasan_save_stack+0x33/0x60 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x2e4/0x6f0 mm/slub.c:5489 _kmalloc_noprof include/linux/slab.h:988 [inline] _kzalloc_noprof include/linux/slab.h:1309 [inline] binderfs_binder_device_create.isra.0+0x17a/0x990 drivers/android/binderfs.c:148 binder_ctl_ioctl+0x186/0x1b0 drivers/android/binderfs.c:241 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x116/0x800 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 11389: kasan_save_stack+0x33/0x60 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2677 [inline] slab_free mm/slub.c:6377 [inline] kfree+0x2fc/0x6e0 mm/slub.c:6692 binderf ---truncated---

Where it lives

The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.

drivers/android/binderfs.c

What this is

ANDROID DRIVERSMAINTAINERS section matched on drivers/android/ · linux-kernel@vger.kernel.org · Supported

Kernel module

none to look for. The file would have gone into binderfs, and Debian does not compile it into that module, so finding binderfs in lsmod would say nothing about this CVE.

Check it on the machine

grep -w CONFIG_ANDROID_BINDERFS /boot/config-$(uname -r)

Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.

Show whether Debian builds this, per release

Debian does not build this code. In 4 releases below, every kernel flavour Debian publishes has the switch off, so the vulnerable file is compiled into no kernel binary Debian ships.

• bookworm, trixie, forky, sidn

n

not enabled on any flavour - this release does not build the code

Build switch

CONFIG_ANDROID_BINDERFS

From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages

Signals

Published

2026-10-18 (today)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

not scored

CISA KEV

not listedthe KEV catalogue

Debian urgency

unimportantsource

Subsystem

drivers/android

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
6.19	7.2.10	885bbbe52d31
6.19	7.3	30d15f44a9e5