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CVE-2026-23407NVD status: Analyzed

Linux: Out-of-bounds Read

Published Updated By the CyberSecBulletin desk

CVE-2026-23407 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 555829fd91eaf0711e369b0a92aecb0f0aa3281f, a75e12ca90c9e70ba10fee1be2f63cdd63d91a7c, 22094c996968a7c5b59cd3fc9fcbdfdd46d02fec as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.18% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 555829fd91eaf0711e369b0a92aecb0f0aa3281f or a75e12ca90c9e70ba10fee1be2f63cdd63d91a7c or 22094c996968a7c5b59cd3fc9fcbdfdd46d02fec or 7c7cf05e0606f554c467e3a4dc49e2e578a755b4, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.253 or 5.15.203 or 6.1.169 or 6.6.130, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 up to, but not including, 555829fd91eaf0711e369b0a92aecb0f0aa3281f; 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 up to, but not including, a75e12ca90c9e70ba10fee1be2f63cdd63d91a7c; 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 up to, but not including, 22094c996968a7c5b59cd3fc9fcbdfdd46d02fec; 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 up to, but not including, 7c7cf05e0606f554c467e3a4dc49e2e578a755b4; 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 up to, but not including, 76b4d36c5122866452d34d8f79985e191f9c3831; 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 up to, but not including, 5a68e46dfe0c8c8ffc6f425ebc4cae6238566ecc; 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 up to, but not including, f39e126e56c6ec1930fae51ad6bca3dae2a4c3ed; 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 up to, but not including, d352873bbefa7eb39995239d0b44ccdf8aaa79a4; and 1 more ranges555829fd91eaf0711e369b0a92aecb0f0aa3281f, a75e12ca90c9e70ba10fee1be2f63cdd63d91a7c, 22094c996968a7c5b59cd3fc9fcbdfdd46d02fec, 7c7cf05e0606f554c467e3a4dc49e2e578a755b4, 76b4d36c5122866452d34d8f79985e191f9c3831, 5a68e46dfe0c8c8ffc6f425ebc4cae6238566ecc
LinuxLinux Kernel4.17.1 up to, but not including, 5.10.253; 5.11 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.169; 6.2 up to, but not including, 6.6.130; 6.7 up to, but not including, 6.12.77; 6.13 up to, but not including, 6.18.18; 6.19 up to, but not including, 6.19.8; 4.17; and 1 more ranges5.10.253, 5.15.203, 6.1.169, 6.6.130, 6.12.77, 6.18.18

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.

Official 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: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Read

The product reads data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that provides appropriate memory abstractions.

More Out-of-bounds Read vulnerabilities (CWE-125)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Read vulnerabilities

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