How severe is CVE-2024-56548?

CVE-2024-56548 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2024-56548 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2024-56548?

CVE-2024-56548 affects Linux Linux Kernel. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2024-56548?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2024-56548 have an EU (EUVD) identifier?

Yes. CVE-2024-56548 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-53196.

When was CVE-2024-56548 published?

CVE-2024-56548 was published on 2024-12-27 and last updated on 2026-06-17.

CVE-2024-56548

CVE-2024-56548 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

Severity: High (CVSS 3.x base score 7.8)
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2024-53196
Weakness: CWE-787
Affected product: Linux Linux Kernel
Published: 2024-12-27
Last modified: 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: hfsplus: don't query the device logical block size multiple times Devices block sizes may change. One of these cases is a loop device by using ioctl LOOP_SET_BLOCK_SIZE. While this may cause other issues like IO being rejected, in the case of hfsplus, it will allocate a block by using that size and potentially write out-of-bounds when hfsplus_read_wrapper calls hfsplus_submit_bio and the latter function reads a different io_size. Using a new min_io_size initally set to sb_min_blocksize works for the purposes of the original fix, since it will be set to the max between HFSPLUS_SECTOR_SIZE and the first seen logical block size. We still use the max between HFSPLUS_SECTOR_SIZE and min_io_size in case the latter is not initialized. Tested by mounting an hfsplus filesystem with loop block sizes 512, 1024 and 4096. The produced KASAN report before the fix looks like this: [ 419.944641] ================================================================== [ 419.945655] BUG: KASAN: slab-use-after-free in hfsplus_read_wrapper+0x659/0xa0a [ 419.946703] Read of size 2 at addr ffff88800721fc00 by task repro/10678 [ 419.947612] [ 419.947846] CPU: 0 UID: 0 PID: 10678 Comm: repro Not tainted 6.12.0-rc5-00008-gdf56e0f2f3ca #84 [ 419.949007] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014 [ 419.950035] Call Trace: [ 419.950384] <TASK> [ 419.950676] dump_stack_lvl+0x57/0x78 [ 419.951212] ? hfsplus_read_wrapper+0x659/0xa0a [ 419.951830] print_report+0x14c/0x49e [ 419.952361] ? __virt_addr_valid+0x267/0x278 [ 419.952979] ? kmem_cache_debug_flags+0xc/0x1d [ 419.953561] ? hfsplus_read_wrapper+0x659/0xa0a [ 419.954231] kasan_report+0x89/0xb0 [ 419.954748] ? hfsplus_read_wrapper+0x659/0xa0a [ 419.955367] hfsplus_read_wrapper+0x659/0xa0a [ 419.955948] ? __pfx_hfsplus_read_wrapper+0x10/0x10 [ 419.956618] ? do_raw_spin_unlock+0x59/0x1a9 [ 419.957214] ? _raw_spin_unlock+0x1a/0x2e [ 419.957772] hfsplus_fill_super+0x348/0x1590 [ 419.958355] ? hlock_class+0x4c/0x109 [ 419.958867] ? __pfx_hfsplus_fill_super+0x10/0x10 [ 419.959499] ? __pfx_string+0x10/0x10 [ 419.960006] ? lock_acquire+0x3e2/0x454 [ 419.960532] ? bdev_name.constprop.0+0xce/0x243 [ 419.961129] ? __pfx_bdev_name.constprop.0+0x10/0x10 [ 419.961799] ? pointer+0x3f0/0x62f [ 419.962277] ? __pfx_pointer+0x10/0x10 [ 419.962761] ? vsnprintf+0x6c4/0xfba [ 419.963178] ? __pfx_vsnprintf+0x10/0x10 [ 419.963621] ? setup_bdev_super+0x376/0x3b3 [ 419.964029] ? snprintf+0x9d/0xd2 [ 419.964344] ? __pfx_snprintf+0x10/0x10 [ 419.964675] ? lock_acquired+0x45c/0x5e9 [ 419.965016] ? set_blocksize+0x139/0x1c1 [ 419.965381] ? sb_set_blocksize+0x6d/0xae [ 419.965742] ? __pfx_hfsplus_fill_super+0x10/0x10 [ 419.966179] mount_bdev+0x12f/0x1bf [ 419.966512] ? __pfx_mount_bdev+0x10/0x10 [ 419.966886] ? vfs_parse_fs_string+0xce/0x111 [ 419.967293] ? __pfx_vfs_parse_fs_string+0x10/0x10 [ 419.967702] ? __pfx_hfsplus_mount+0x10/0x10 [ 419.968073] legacy_get_tree+0x104/0x178 [ 419.968414] vfs_get_tree+0x86/0x296 [ 419.968751] path_mount+0xba3/0xd0b [ 419.969157] ? __pfx_path_mount+0x10/0x10 [ 419.969594] ? kmem_cache_free+0x1e2/0x260 [ 419.970311] do_mount+0x99/0xe0 [ 419.970630] ? __pfx_do_mount+0x10/0x10 [ 419.971008] __do_sys_mount+0x199/0x1c9 [ 419.971397] do_syscall_64+0xd0/0x135 [ 419.971761] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 419.972233] RIP: 0033:0x7c3cb812972e [ 419.972564] Code: 48 8b 0d f5 46 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d c2 46 0d 00 f7 d8 64 89 01 48 [ 419.974371] RSP: 002b:00007ffe30632548 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5 [ 419.975048] RAX: ffffffffffffffda RBX: 00007ffe306328d8 RCX: 00007c3cb812972e [ 419.975701] RDX: 0000000020000000 RSI: 0000000020000c80 RDI: ---truncated---

Frequently asked questions

What is CVE-2024-56548?: In the Linux kernel, the following vulnerability has been resolved: hfsplus: don't query the device logical block size multiple times Devices block sizes may change. One of these cases is a loop device by using ioctl LOOP_SET_BLOCK_SIZE. While this may cause other issues like IO being rejected, in the case of hfsplus, it will allocate a block by using that size and potentially write out-of-bounds when hfsplus_read_wrapper calls hfsplus_submit_bio and the latter function reads a different io_size. Using a new min_io_size initally set to sb_min_blocksize works for the purposes of the original fix, since it will be set to the max between HFSPLUS_SECTOR_SIZE and the first seen logical block size. We still use the max between HFSPLUS_SECTOR_SIZE and min_io_size in case the latter is not initialized. Tested by mounting an hfsplus filesystem with loop block sizes 512, 1024 and 4096. The produced KASAN report before the fix looks like this: [ 419.944641] ================================================================== [ 419.945655] BUG: KASAN: slab-use-after-free in hfsplus_read_wrapper+0x659/0xa0a [ 419.946703] Read of size 2 at addr ffff88800721fc00 by task repro/10678 [ 419.947612] [ 419.947846] CPU: 0 UID: 0 PID: 10678 Comm: repro Not tainted 6.12.0-rc5-00008-gdf56e0f2f3ca #84 [ 419.949007] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014 [ 419.950035] Call Trace: [ 419.950384] <TASK> [ 419.950676] dump_stack_lvl+0x57/0x78 [ 419.951212] ? hfsplus_read_wrapper+0x659/0xa0a [ 419.951830] print_report+0x14c/0x49e [ 419.952361] ? __virt_addr_valid+0x267/0x278 [ 419.952979] ? kmem_cache_debug_flags+0xc/0x1d [ 419.953561] ? hfsplus_read_wrapper+0x659/0xa0a [ 419.954231] kasan_report+0x89/0xb0 [ 419.954748] ? hfsplus_read_wrapper+0x659/0xa0a [ 419.955367] hfsplus_read_wrapper+0x659/0xa0a [ 419.955948] ? __pfx_hfsplus_read_wrapper+0x10/0x10 [ 419.956618] ? do_raw_spin_unlock+0x59/0x1a9 [ 419.957214] ? _raw_spin_unlock+0x1a/0x2e [ 419.957772] hfsplus_fill_super+0x348/0x1590 [ 419.958355] ? hlock_class+0x4c/0x109 [ 419.958867] ? __pfx_hfsplus_fill_super+0x10/0x10 [ 419.959499] ? __pfx_string+0x10/0x10 [ 419.960006] ? lock_acquire+0x3e2/0x454 [ 419.960532] ? bdev_name.constprop.0+0xce/0x243 [ 419.961129] ? __pfx_bdev_name.constprop.0+0x10/0x10 [ 419.961799] ? pointer+0x3f0/0x62f [ 419.962277] ? __pfx_pointer+0x10/0x10 [ 419.962761] ? vsnprintf+0x6c4/0xfba [ 419.963178] ? __pfx_vsnprintf+0x10/0x10 [ 419.963621] ? setup_bdev_super+0x376/0x3b3 [ 419.964029] ? snprintf+0x9d/0xd2 [ 419.964344] ? __pfx_snprintf+0x10/0x10 [ 419.964675] ? lock_acquired+0x45c/0x5e9 [ 419.965016] ? set_blocksize+0x139/0x1c1 [ 419.965381] ? sb_set_blocksize+0x6d/0xae [ 419.965742] ? __pfx_hfsplus_fill_super+0x10/0x10 [ 419.966179] mount_bdev+0x12f/0x1bf [ 419.966512] ? __pfx_mount_bdev+0x10/0x10 [ 419.966886] ? vfs_parse_fs_string+0xce/0x111 [ 419.967293] ? __pfx_vfs_parse_fs_string+0x10/0x10 [ 419.967702] ? __pfx_hfsplus_mount+0x10/0x10 [ 419.968073] legacy_get_tree+0x104/0x178 [ 419.968414] vfs_get_tree+0x86/0x296 [ 419.968751] path_mount+0xba3/0xd0b [ 419.969157] ? __pfx_path_mount+0x10/0x10 [ 419.969594] ? kmem_cache_free+0x1e2/0x260 [ 419.970311] do_mount+0x99/0xe0 [ 419.970630] ? __pfx_do_mount+0x10/0x10 [ 419.971008] __do_sys_mount+0x199/0x1c9 [ 419.971397] do_syscall_64+0xd0/0x135 [ 419.971761] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 419.972233] RIP: 0033:0x7c3cb812972e [ 419.972564] Code: 48 8b 0d f5 46 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d c2 46 0d 00 f7 d8 64 89 01 48 [ 419.974371] RSP: 002b:00007ffe30632548 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5 [ 419.975048] RAX: ffffffffffffffda RBX: 00007ffe306328d8 RCX: 00007c3cb812972e [ 419.975701] RDX: 0000000020000000 RSI: 0000000020000c80 RDI: ---truncated---
How severe is CVE-2024-56548?: CVE-2024-56548 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2024-56548 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2024-56548?: CVE-2024-56548 affects Linux Linux Kernel. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2024-56548?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2024-56548 have an EU (EUVD) identifier?: Yes. CVE-2024-56548 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-53196.
When was CVE-2024-56548 published?: CVE-2024-56548 was published on 2024-12-27 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

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