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CVE-2026-23407— apparmor: fix missing bounds check on DEFAULT table in verify_dfa()

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于verify_dfa函数缺少对DEFAULT表的边界检查，可能导致越界读取和写入。

CVSS 7.8 · High EPSS 0.18% · P7

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3< 555829fd91eaf0711e369b0a92aecb0f0aa3281f affected
031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3< a75e12ca90c9e70ba10fee1be2f63cdd63d91a7c affected
031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3< 22094c996968a7c5b59cd3fc9fcbdfdd46d02fec affected
031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3< 7c7cf05e0606f554c467e3a4dc49e2e578a755b4 affected
031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3< 76b4d36c5122866452d34d8f79985e191f9c3831 affected
031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3< 5a68e46dfe0c8c8ffc6f425ebc4cae6238566ecc affected
031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3< f39e126e56c6ec1930fae51ad6bca3dae2a4c3ed affected
031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3< d352873bbefa7eb39995239d0b44ccdf8aaa79a4 affected
… +10 more rows
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I. Basic Information for CVE-2026-23407

Vulnerability Information
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Vulnerability Title
apparmor: fix missing bounds check on DEFAULT table in verify_dfa()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: apparmor: fix missing bounds check on DEFAULT table in verify_dfa() The verify_dfa() function only checks DEFAULT_TABLE bounds when the state is not differentially encoded. When the verification loop traverses the differential encoding chain, it reads k = DEFAULT_TABLE[j] and uses k as an array index without validation. A malformed DFA with DEFAULT_TABLE[j] >= state_count, therefore, causes both out-of-bounds reads and writes. [ 57.179855] ================================================================== [ 57.180549] BUG: KASAN: slab-out-of-bounds in verify_dfa+0x59a/0x660 [ 57.180904] Read of size 4 at addr ffff888100eadec4 by task su/993 [ 57.181554] CPU: 1 UID: 0 PID: 993 Comm: su Not tainted 6.19.0-rc7-next-20260127 #1 PREEMPT(lazy) [ 57.181558] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 57.181563] Call Trace: [ 57.181572] <TASK> [ 57.181577] dump_stack_lvl+0x5e/0x80 [ 57.181596] print_report+0xc8/0x270 [ 57.181605] ? verify_dfa+0x59a/0x660 [ 57.181608] kasan_report+0x118/0x150 [ 57.181620] ? verify_dfa+0x59a/0x660 [ 57.181623] verify_dfa+0x59a/0x660 [ 57.181627] aa_dfa_unpack+0x1610/0x1740 [ 57.181629] ? __kmalloc_cache_noprof+0x1d0/0x470 [ 57.181640] unpack_pdb+0x86d/0x46b0 [ 57.181647] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181653] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181656] ? aa_unpack_nameX+0x1a8/0x300 [ 57.181659] aa_unpack+0x20b0/0x4c30 [ 57.181662] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181664] ? stack_depot_save_flags+0x33/0x700 [ 57.181681] ? kasan_save_track+0x4f/0x80 [ 57.181683] ? kasan_save_track+0x3e/0x80 [ 57.181686] ? __kasan_kmalloc+0x93/0xb0 [ 57.181688] ? __kvmalloc_node_noprof+0x44a/0x780 [ 57.181693] ? aa_simple_write_to_buffer+0x54/0x130 [ 57.181697] ? policy_update+0x154/0x330 [ 57.181704] aa_replace_profiles+0x15a/0x1dd0 [ 57.181707] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181710] ? __kvmalloc_node_noprof+0x44a/0x780 [ 57.181712] ? aa_loaddata_alloc+0x77/0x140 [ 57.181715] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181717] ? _copy_from_user+0x2a/0x70 [ 57.181730] policy_update+0x17a/0x330 [ 57.181733] profile_replace+0x153/0x1a0 [ 57.181735] ? rw_verify_area+0x93/0x2d0 [ 57.181740] vfs_write+0x235/0xab0 [ 57.181745] ksys_write+0xb0/0x170 [ 57.181748] do_syscall_64+0x8e/0x660 [ 57.181762] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 57.181765] RIP: 0033:0x7f6192792eb2 Remove the MATCH_FLAG_DIFF_ENCODE condition to validate all DEFAULT_TABLE entries unconditionally.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于verify_dfa函数缺少对DEFAULT表的边界检查，可能导致越界读取和写入。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 ~ 555829fd91eaf0711e369b0a92aecb0f0aa3281f -
Linux Linux 4.17 -

II. Public POCs for CVE-2026-23407

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III. Intelligence Information for CVE-2026-23407

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Same Patch Batch · Linux · 2026-04-01 · 11 CVEs total

CVE-2026-23411 7.8 HIGH apparmor: fix race between freeing data and fs accessing it
CVE-2026-23410 7.8 HIGH apparmor: fix race on rawdata dereference
CVE-2026-23408 7.8 HIGH apparmor: Fix double free of ns_name in aa_replace_profiles()
CVE-2026-23406 7.8 HIGH apparmor: fix side-effect bug in match_char() macro usage
CVE-2026-23409 apparmor: fix differential encoding verification
CVE-2026-23405 apparmor: fix: limit the number of levels of policy namespaces
CVE-2026-23404 apparmor: replace recursive profile removal with iterative approach
CVE-2026-23403 apparmor: fix memory leak in verify_header
CVE-2026-23402 KVM: x86/mmu: Only WARN in direct MMUs when overwriting shadow-present SPTE
CVE-2026-23401 KVM: x86/mmu: Drop/zap existing present SPTE even when creating an MMIO SPTE

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23407

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