In the Linux kernel, the following vulnerability has been resolved: fs: udf: fix OOB read in lengthAllocDescs handling When parsing Allocation… (CVE-2025-40044)
In the Linux kernel, the following vulnerability has been resolved: fs: udf: fix OOB read in lengthAllocDescs handling When parsing Allocation Extent Descriptor, lengthAllocDescs comes from on-disk data and must be validated against the block size. Crafted or corrupted images may set lengthAllocDescs so that the total descriptor length (sizeof(allocExtDesc) + lengthAllocDescs) exceeds the buffer, leading udf_update_tag() to call crc_itu_t() on out-of-bounds memory and trigger a KASAN use-after-free read. BUG: KASAN: use-after-free in crc_itu_t+0x1d5/0x2b0 lib/crc-itu-t.c:60 Read of size 1 at addr ffff888041e7d000 by task syz-executor317/5309 CPU: 0 UID: 0 PID: 5309 Comm: syz-executor317 Not tainted 6.12.0-rc4-syzkaller-00261-g850925a8133c #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:377 [inline] print_report+0x169/0x550 mm/kasan/report.c:488 kasan_report+0x143/0x180 mm/kasan/report.c:601 crc_itu_t+0x1d5/0x2b0 lib/crc-itu-t.c:60 udf_update_tag+0x70/0x6a0 fs/udf/misc.c:261 udf_write_aext+0x4d8/0x7b0 fs/udf/inode.c:2179 extent_trunc+0x2f7/0x4a0 fs/udf/truncate.c:46 udf_truncate_tail_extent+0x527/0x7e0 fs/udf/truncate.c:106 udf_release_file+0xc1/0x120 fs/udf/file.c:185 __fput+0x23f/0x880 fs/file_table.c:431 task_work_run+0x24f/0x310 kernel/task_work.c:239 exit_task_work include/linux/task_work.h:43 [inline] do_exit+0xa2f/0x28e0 kernel/exit.c:939 do_group_exit+0x207/0x2c0 kernel/exit.c:1088 __do_sys_exit_group kernel/exit.c:1099 [inline] __se_sys_exit_group kernel/exit.c:1097 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1097 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK> Validate the computed total length against epos->bh->b_size. Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
AI Analysis
Technical Summary
CVE-2025-40044 is a high-severity vulnerability in the Linux kernel's UDF filesystem code where lengthAllocDescs, derived from on-disk data, was not properly validated against the block size. This flaw allowed crafted or corrupted UDF images to cause the udf_update_tag() function to call crc_itu_t() on out-of-bounds memory, triggering a KASAN use-after-free read. The vulnerability was discovered by the Linux Verification Center using Syzkaller and is fixed by validating the computed total length against the block size (epos->bh->b_size).
Potential Impact
Exploitation of this vulnerability can lead to a kernel use-after-free read, which may cause system instability, crashes, or potentially allow an attacker to execute arbitrary code with kernel privileges. The CVSS vector indicates local attack vector with low complexity, no privileges required, user interaction required, unchanged scope, and high impact on confidentiality, integrity, and availability.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Users should monitor official Linux kernel releases and apply updates that address CVE-2025-40044 once available. Until patched, avoid mounting or processing untrusted or potentially corrupted UDF filesystem images.
In the Linux kernel, the following vulnerability has been resolved: fs: udf: fix OOB read in lengthAllocDescs handling When parsing Allocation… (CVE-2025-40044)
Description
In the Linux kernel, the following vulnerability has been resolved: fs: udf: fix OOB read in lengthAllocDescs handling When parsing Allocation Extent Descriptor, lengthAllocDescs comes from on-disk data and must be validated against the block size. Crafted or corrupted images may set lengthAllocDescs so that the total descriptor length (sizeof(allocExtDesc) + lengthAllocDescs) exceeds the buffer, leading udf_update_tag() to call crc_itu_t() on out-of-bounds memory and trigger a KASAN use-after-free read. BUG: KASAN: use-after-free in crc_itu_t+0x1d5/0x2b0 lib/crc-itu-t.c:60 Read of size 1 at addr ffff888041e7d000 by task syz-executor317/5309 CPU: 0 UID: 0 PID: 5309 Comm: syz-executor317 Not tainted 6.12.0-rc4-syzkaller-00261-g850925a8133c #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:377 [inline] print_report+0x169/0x550 mm/kasan/report.c:488 kasan_report+0x143/0x180 mm/kasan/report.c:601 crc_itu_t+0x1d5/0x2b0 lib/crc-itu-t.c:60 udf_update_tag+0x70/0x6a0 fs/udf/misc.c:261 udf_write_aext+0x4d8/0x7b0 fs/udf/inode.c:2179 extent_trunc+0x2f7/0x4a0 fs/udf/truncate.c:46 udf_truncate_tail_extent+0x527/0x7e0 fs/udf/truncate.c:106 udf_release_file+0xc1/0x120 fs/udf/file.c:185 __fput+0x23f/0x880 fs/file_table.c:431 task_work_run+0x24f/0x310 kernel/task_work.c:239 exit_task_work include/linux/task_work.h:43 [inline] do_exit+0xa2f/0x28e0 kernel/exit.c:939 do_group_exit+0x207/0x2c0 kernel/exit.c:1088 __do_sys_exit_group kernel/exit.c:1099 [inline] __se_sys_exit_group kernel/exit.c:1097 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1097 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK> Validate the computed total length against epos->bh->b_size. Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
CVSS v3.1
Score 7.8high
Affected software
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2025-40044 is a high-severity vulnerability in the Linux kernel's UDF filesystem code where lengthAllocDescs, derived from on-disk data, was not properly validated against the block size. This flaw allowed crafted or corrupted UDF images to cause the udf_update_tag() function to call crc_itu_t() on out-of-bounds memory, triggering a KASAN use-after-free read. The vulnerability was discovered by the Linux Verification Center using Syzkaller and is fixed by validating the computed total length against the block size (epos->bh->b_size).
Potential Impact
Exploitation of this vulnerability can lead to a kernel use-after-free read, which may cause system instability, crashes, or potentially allow an attacker to execute arbitrary code with kernel privileges. The CVSS vector indicates local attack vector with low complexity, no privileges required, user interaction required, unchanged scope, and high impact on confidentiality, integrity, and availability.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Users should monitor official Linux kernel releases and apply updates that address CVE-2025-40044 once available. Until patched, avoid mounting or processing untrusted or potentially corrupted UDF filesystem images.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-4j58-87g3-fv33
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2025-40044"]
- Database Specific Severity
- HIGH
- Cvss Version
- 3.1
Threat ID: 6a6b72d79c2644c7f847b7ef
Added to database: 07/30/2026, 15:50:47 UTC
Last enriched: 07/30/2026, 15:57:33 UTC
Last updated: 09/10/2026, 19:36:50 UTC
Views: 20
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