Linux Kernel up to 6.17.5 hfs hfsplus_bmap_alloc out-of-bounds

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2.5$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.17.5. Impacted is the function hfsplus_bmap_alloc of the component hfs. This manipulation causes out-of-bounds. This vulnerability is registered as CVE-2025-40349. No exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.17.5. It has been declared as problematic. Affected by this vulnerability is the function hfsplus_bmap_alloc of the component hfs. The manipulation with an unknown input leads to a out-of-bounds vulnerability. The CWE definition for the vulnerability is CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect confidentiality. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: hfs: validate record offset in hfsplus_bmap_alloc hfsplus_bmap_alloc can trigger a crash if a record offset or length is larger than node_size [ 15.264282] BUG: KASAN: slab-out-of-bounds in hfsplus_bmap_alloc+0x887/0x8b0 [ 15.265192] Read of size 8 at addr ffff8881085ca188 by task test/183 [ 15.265949] [ 15.266163] CPU: 0 UID: 0 PID: 183 Comm: test Not tainted 6.17.0-rc2-gc17b750b3ad9 #14 PREEMPT(voluntary) [ 15.266165] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 15.266167] Call Trace: [ 15.266168] <TASK> [ 15.266169] dump_stack_lvl+0x53/0x70 [ 15.266173] print_report+0xd0/0x660 [ 15.266181] kasan_report+0xce/0x100 [ 15.266185] hfsplus_bmap_alloc+0x887/0x8b0 [ 15.266208] hfs_btree_inc_height.isra.0+0xd5/0x7c0 [ 15.266217] hfsplus_brec_insert+0x870/0xb00 [ 15.266222] __hfsplus_ext_write_extent+0x428/0x570 [ 15.266225] __hfsplus_ext_cache_extent+0x5e/0x910 [ 15.266227] hfsplus_ext_read_extent+0x1b2/0x200 [ 15.266233] hfsplus_file_extend+0x5a7/0x1000 [ 15.266237] hfsplus_get_block+0x12b/0x8c0 [ 15.266238] __block_write_begin_int+0x36b/0x12c0 [ 15.266251] block_write_begin+0x77/0x110 [ 15.266252] cont_write_begin+0x428/0x720 [ 15.266259] hfsplus_write_begin+0x51/0x100 [ 15.266262] cont_write_begin+0x272/0x720 [ 15.266270] hfsplus_write_begin+0x51/0x100 [ 15.266274] generic_perform_write+0x321/0x750 [ 15.266285] generic_file_write_iter+0xc3/0x310 [ 15.266289] __kernel_write_iter+0x2fd/0x800 [ 15.266296] dump_user_range+0x2ea/0x910 [ 15.266301] elf_core_dump+0x2a94/0x2ed0 [ 15.266320] vfs_coredump+0x1d85/0x45e0 [ 15.266349] get_signal+0x12e3/0x1990 [ 15.266357] arch_do_signal_or_restart+0x89/0x580 [ 15.266362] irqentry_exit_to_user_mode+0xab/0x110 [ 15.266364] asm_exc_page_fault+0x26/0x30 [ 15.266366] RIP: 0033:0x41bd35 [ 15.266367] Code: bc d1 f3 0f 7f 27 f3 0f 7f 6f 10 f3 0f 7f 77 20 f3 0f 7f 7f 30 49 83 c0 0f 49 29 d0 48 8d 7c 17 31 e9 9f 0b 00 00 66 0f ef c0 <f3> 0f 6f 0e f3 0f 6f 56 10 66 0f 74 c1 66 0f d7 d0 49 83 f8f [ 15.266369] RSP: 002b:00007ffc9e62d078 EFLAGS: 00010283 [ 15.266371] RAX: 00007ffc9e62d100 RBX: 0000000000000000 RCX: 0000000000000000 [ 15.266372] RDX: 00000000000000e0 RSI: 0000000000000000 RDI: 00007ffc9e62d100 [ 15.266373] RBP: 0000400000000040 R08: 00000000000000e0 R09: 0000000000000000 [ 15.266374] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 [ 15.266375] R13: 0000000000000000 R14: 0000000000000000 R15: 0000400000000000 [ 15.266376] </TASK> When calling hfsplus_bmap_alloc to allocate a free node, this function first retrieves the bitmap from header node and map node using node->page together with the offset and length from hfs_brec_lenoff ``` len = hfs_brec_lenoff(node, 2, &off16); off = off16; off += node->page_offset; pagep = node->page + (off >> PAGE_SHIFT); data = kmap_local_page(*pagep); ``` However, if the retrieved offset or length is invalid(i.e. exceeds node_size), the code may end up accessing pages outside the allocated range for this node. This patch adds proper validation of both offset and length before use, preventing out-of-bounds page access. Move is_bnode_offset_valid and check_and_correct_requested_length to hfsplus_fs.h, as they may be required by other functions.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2025-40349 since 04/16/2025. The exploitation appears to be difficult. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 279022 (Linux Distros Unpatched Vulnerability : CVE-2025-40349), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.4.301, 5.10.246, 5.15.196, 6.1.158, 6.6.115, 6.12.56 or 6.17.6 eliminates this vulnerability. Applying the patch f7d9f600c7c3ff5dab36181a388af55f2c95604c/40dfe7a4215a1f20842561ffaf5a6f83a987e75b/418e48cab99c52c1760636a4dbe464bf6db2018b/0058d20d76182861dbdd8fd6e2dd8d18d6d3becf/4f40a2b3969daf10dca4dea6f6dd0e813f79b227/17ed51cfce6c62cffb97059ef392ad2e0245806e/068a46df3e6acc68fb9db0a6313ab379a11ecd6f/738d5a51864ed8d7a68600b8c0c63fe6fe5c4f20 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (279022) and CERT Bund (WID-SEC-2025-2868). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • Open Source Linux Kernel

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 2.6
VulDB Meta Temp Score: 2.5

VulDB Base Score: 2.6
VulDB Temp Score: 2.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds
CWE: CWE-125 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 279022
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-40349

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.4.301/5.10.246/5.15.196/6.1.158/6.6.115/6.12.56/6.17.6
Patch: f7d9f600c7c3ff5dab36181a388af55f2c95604c/40dfe7a4215a1f20842561ffaf5a6f83a987e75b/418e48cab99c52c1760636a4dbe464bf6db2018b/0058d20d76182861dbdd8fd6e2dd8d18d6d3becf/4f40a2b3969daf10dca4dea6f6dd0e813f79b227/17ed51cfce6c62cffb97059ef392ad2e0245806e/068a46df3e6acc68fb9db0a6313ab379a11ecd6f/738d5a51864ed8d7a68600b8c0c63fe6fe5c4f20

Timelineinfo

04/16/2025 CVE reserved
12/16/2025 +244 days Advisory disclosed
12/16/2025 +0 days VulDB entry created
02/21/2026 +67 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-40349 (🔒)
GCVE (CVE): GCVE-0-2025-40349
GCVE (VulDB): GCVE-100-336715
CERT Bund: WID-SEC-2025-2868 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 12/16/2025 15:04
Updated: 02/21/2026 03:22
Changes: 12/16/2025 15:04 (59), 12/16/2025 15:47 (1), 12/18/2025 17:45 (2), 01/14/2026 01:43 (7), 01/19/2026 13:19 (1), 02/02/2026 12:46 (1), 02/16/2026 10:48 (1), 02/21/2026 03:22 (1)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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