CVE-2025-40088 hfsplus: fix slab-out-of-bounds read in hfsplus_strcasecmp()
A slab-out-of-bounds read in the Linux kernel's HFS+ filesystem driver allows attackers to cause a denial of service or leak sensitive memory information.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-40088?
CVE-2025-40088 is a high-severity memory corruption vulnerability in Linux, published on 30 Oct 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
hfsplus: fix slab-out-of-bounds read in hfsplus_strcasecmp()
The hfsplus_strcasecmp() logic can trigger the issue:
[ 117.317703][ T9855] ================================================================== [ 117.318353][ T9855] BUG: KASAN: slab-out-of-bounds in hfsplus_strcasecmp+0x1bc/0x490 [ 117.318991][ T9855] Read of size 2 at addr ffff88802160f40c by task repro/9855 [ 117.319577][ T9855] [ 117.319773][ T9855] CPU: 0 UID: 0 PID: 9855 Comm: repro Not tainted 6.17.0-rc6 #33 PREEMPT(full) [ 117.319780][ T9855] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 117.319783][ T9855] Call Trace: [ 117.319785][ T9855] <TASK> [ 117.319788][ T9855] dump_stack_lvl+0x1c1/0x2a0 [ 117.319795][ T9855] ? __virt_addr_valid+0x1c8/0x5c0 [ 117.319803][ T9855] ? __pfx_dump_stack_lvl+0x10/0x10 [ 117.319808][ T9855] ? rcu_is_watching+0x15/0xb0 [ 117.319816][ T9855] ? lock_release+0x4b/0x3e0 [ 117.319821][ T9855] ? __kasan_check_byte+0x12/0x40 [ 117.319828][ T9855] ? __virt_addr_valid+0x1c8/0x5c0 [ 117.319835][ T9855] ? __virt_addr_valid+0x4a5/0x5c0 [ 117.319842][ T9855] print_report+0x17e/0x7e0 [ 117.319848][ T9855] ? __virt_addr_valid+0x1c8/0x5c0 [ 117.319855][ T9855] ? __virt_addr_valid+0x4a5/0x5c0 [ 117.319862][ T9855] ? __phys_addr+0xd3/0x180 [ 117.319869][ T9855] ? hfsplus_strcasecmp+0x1bc/0x490 [ 117.319876][ T9855] kasan_report+0x147/0x180 [ 117.319882][ T9855] ? hfsplus_strcasecmp+0x1bc/0x490 [ 117.319891][ T9855] hfsplus_strcasecmp+0x1bc/0x490 [ 117.319900][ T9855] ? __pfx_hfsplus_cat_case_cmp_key+0x10/0x10 [ 117.319906][ T9855] hfs_find_rec_by_key+0xa9/0x1e0 [ 117.319913][ T9855] __hfsplus_brec_find+0x18e/0x470 [ 117.319920][ T9855] ? __pfx_hfsplus_bnode_find+0x10/0x10 [ 117.319926][ T9855] ? __pfx_hfs_find_rec_by_key+0x10/0x10 [ 117.319933][ T9855] ? __pfx___hfsplus_brec_find+0x10/0x10 [ 117.319942][ T9855] hfsplus_brec_find+0x28f/0x510 [ 117.319949][ T9855] ? __pfx_hfs_find_rec_by_key+0x10/0x10 [ 117.319956][ T9855] ? __pfx_hfsplus_brec_find+0x10/0x10 [ 117.319963][ T9855] ? __kmalloc_noprof+0x2a9/0x510 [ 117.319969][ T9855] ? hfsplus_find_init+0x8c/0x1d0 [ 117.319976][ T9855] hfsplus_brec_read+0x2b/0x120 [ 117.319983][ T9855] hfsplus_lookup+0x2aa/0x890 [ 117.319990][ T9855] ? __pfx_hfsplus_lookup+0x10/0x10 [ 117.320003][ T9855] ? d_alloc_parallel+0x2f0/0x15e0 [ 117.320008][ T9855] ? __lock_acquire+0xaec/0xd80 [ 117.320013][ T9855] ? __pfx_d_alloc_parallel+0x10/0x10 [ 117.320019][ T9855] ? __raw_spin_lock_init+0x45/0x100 [ 117.320026][ T9855] ? __init_waitqueue_head+0xa9/0x150 [ 117.320034][ T9855] __lookup_slow+0x297/0x3d0 [ 117.320039][ T9855] ? __pfx___lookup_slow+0x10/0x10 [ 117.320045][ T9855] ? down_read+0x1ad/0x2e0 [ 117.320055][ T9855] lookup_slow+0x53/0x70 [ 117.320065][ T9855] walk_component+0x2f0/0x430 [ 117.320073][ T9855] path_lookupat+0x169/0x440 [ 117.320081][ T9855] filename_lookup+0x212/0x590 [ 117.320089][ T9855] ? __pfx_filename_lookup+0x10/0x10 [ 117.320098][ T9855] ? strncpy_from_user+0x150/0x290 [ 117.320105][ T9855] ? getname_flags+0x1e5/0x540 [ 117.320112][ T9855] user_path_at+0x3a/0x60 [ 117.320117][ T9855] __x64_sys_umount+0xee/0x160 [ 117.320123][ T9855] ? __pfx___x64_sys_umount+0x10/0x10 [ 117.320129][ T9855] ? do_syscall_64+0xb7/0x3a0 [ 117.320135][ T9855] ? entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 117.320141][ T9855] ? entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 117.320145][ T9855] do_syscall_64+0xf3/0x3a0 [ 117.320150][ T9855] ? exc_page_fault+0x9f/0xf0 [ 117.320154][ T9855] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 117.320158][ T9855] RIP: 0033:0x7f7dd7908b07 [ 117.320163][ T9855] Code: 23 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 08 [ 117.320167][ T9855] RSP: 002b:00007ffd5ebd9698 EFLAGS: 00000202 ---truncated---
Which versions are affected by CVE-2025-40088?
How do I fix CVE-2025-40088?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-40088 being exploited?
There is no known exploitation of CVE-2025-40088 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40088, DEBIAN-CVE-2025-40088, GHSA-9gj3-hmj4-wf3x, ROOT-OS-DEBIAN-11-CVE-2025-40088, ROOT-OS-DEBIAN-12-CVE-2025-40088, ROOT-OS-DEBIAN-13-CVE-2025-40088 and 3 more.