Linux Kernel up to 7.0.3 apparmor match.c aa_dfa_match out-of-bounds

Summaryinfo

A vulnerability labeled as critical has been found in Linux Kernel up to 7.0.3. Affected by this vulnerability is the function aa_dfa_match of the file security/apparmor/match.c of the component apparmor. Such manipulation leads to out-of-bounds. This vulnerability is listed as CVE-2026-46055. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.0.3 and classified as problematic. Affected by this issue is the function aa_dfa_match of the file security/apparmor/match.c of the component apparmor. The manipulation with an unknown input leads to a out-of-bounds vulnerability. Using CWE to declare the problem leads to CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: apparmor: Fix string overrun due to missing termination When booting Ubuntu 26.04 with Linux 7.0-rc4 on an ARM64 Qualcomm Snapdragon X1 we see a string buffer overrun: BUG: KASAN: slab-out-of-bounds in aa_dfa_match (security/apparmor/match.c:535) Read of size 1 at addr ffff0008901cc000 by task snap-update-ns/2120 CPU: 5 UID: 60578 PID: 2120 Comm: snap-update-ns Not tainted 7.0.0-rc4+ #22 PREEMPTLAZY Hardware name: LENOVO 83ED/LNVNB161216, BIOS NHCN60WW 09/11/2025 Call trace: show_stack (arch/arm64/kernel/stacktrace.c:501) (C) dump_stack_lvl (lib/dump_stack.c:122) print_report (mm/kasan/report.c:379 mm/kasan/report.c:482) kasan_report (mm/kasan/report.c:597) __asan_report_load1_noabort (mm/kasan/report_generic.c:378) aa_dfa_match (security/apparmor/match.c:535) match_mnt_path_str (security/apparmor/mount.c:244 security/apparmor/mount.c:336) match_mnt (security/apparmor/mount.c:371) aa_bind_mount (security/apparmor/mount.c:447 (discriminator 4)) apparmor_sb_mount (security/apparmor/lsm.c:719 (discriminator 1)) security_sb_mount (security/security.c:1062 (discriminator 31)) path_mount (fs/namespace.c:4101) __arm64_sys_mount (fs/namespace.c:4172 fs/namespace.c:4361 fs/namespace.c:4338 fs/namespace.c:4338) invoke_syscall.constprop.0 (arch/arm64/kernel/syscall.c:35 arch/arm64/kernel/syscall.c:49) el0_svc_common.constprop.0 (./include/linux/thread_info.h:142 (discriminator 2) arch/arm64/kernel/syscall.c:140 (discriminator 2)) do_el0_svc (arch/arm64/kernel/syscall.c:152) el0_svc (arch/arm64/kernel/entry-common.c:80 arch/arm64/kernel/entry-common.c:725) el0t_64_sync_handler (arch/arm64/kernel/entry-common.c:744) el0t_64_sync (arch/arm64/kernel/entry.S:596) Allocated by task 2120: kasan_save_stack (mm/kasan/common.c:58) kasan_save_track (./arch/arm64/include/asm/current.h:19 mm/kasan/common.c:70 mm/kasan/common.c:79) kasan_save_alloc_info (mm/kasan/generic.c:571) __kasan_kmalloc (mm/kasan/common.c:419) __kmalloc_noprof (./include/linux/kasan.h:263 mm/slub.c:5260 mm/slub.c:5272) aa_get_buffer (security/apparmor/lsm.c:2201) aa_bind_mount (security/apparmor/mount.c:442) apparmor_sb_mount (security/apparmor/lsm.c:719 (discriminator 1)) security_sb_mount (security/security.c:1062 (discriminator 31)) path_mount (fs/namespace.c:4101) __arm64_sys_mount (fs/namespace.c:4172 fs/namespace.c:4361 fs/namespace.c:4338 fs/namespace.c:4338) invoke_syscall.constprop.0 (arch/arm64/kernel/syscall.c:35 arch/arm64/kernel/syscall.c:49) el0_svc_common.constprop.0 (./include/linux/thread_info.h:142 (discriminator 2) arch/arm64/kernel/syscall.c:140 (discriminator 2)) do_el0_svc (arch/arm64/kernel/syscall.c:152) el0_svc (arch/arm64/kernel/entry-common.c:80 arch/arm64/kernel/entry-common.c:725) el0t_64_sync_handler (arch/arm64/kernel/entry-common.c:744) el0t_64_sync (arch/arm64/kernel/entry.S:596) The buggy address belongs to the object at ffff0008901ca000 which belongs to the cache kmalloc-rnd-06-8k of size 8192 The buggy address is located 0 bytes to the right of allocated 8192-byte region [ffff0008901ca000, ffff0008901cc000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x9101c8 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:-1 pincount:0 flags: 0x8000000000000040(head|zone=2) page_type: f5(slab) raw: 8000000000000040 ffff000800016c40 fffffdffe2d14e10 ffff000800015c70 raw: 0000000000000000 0000000800010001 00000000f5000000 0000000000000000 head: 8000000000000040 ffff000800016c40 fffffdffe2d14e10 ffff000800015c70 head: 0000000000000000 0000000800010001 00000000f5000000 0000000000000000 head: 8000000000000003 fffffdffe2407201 fffffdffffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0008901cbf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff0008 ---truncated---

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2026-46055 since 05/13/2026. The exploitation is known to be difficult. Technical details are known, but there is no available exploit.

Upgrading to version 7.0.4 or 7.1-rc1 eliminates this vulnerability. Applying the patch 4b877ef27adc8ec187b0418629169856e7264e01/828bf7929bedcb79b560b5b4e44f22abee07d31b 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.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.0.0
• 7.0.1
• 7.0.2
• 7.0.3

License

• open-source

Website

• Vendor: https://www.kernel.org/

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