Linux Kernel up to 7.0-rc3 apparmor verify_dfa out-of-bounds

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2.5$0-$5k0.00

Summaryinfo

A vulnerability described as critical has been identified in Linux Kernel up to 6.6.129/6.12.76/6.18.17/6.19.7/7.0-rc3. Affected by this vulnerability is the function verify_dfa of the component apparmor. The manipulation results in out-of-bounds. This vulnerability was named CVE-2026-23407. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic has been found in Linux Kernel up to 6.6.129/6.12.76/6.18.17/6.19.7/7.0-rc3. Affected is the function verify_dfa of the component apparmor. The manipulation with an unknown input leads to a out-of-bounds vulnerability. CWE is classifying the issue as CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality. CVE summarizes:

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] [ 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.

The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2026-23407 since 01/13/2026. The exploitability is told to be difficult. Technical details are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 314224 (Ubuntu 20.04 LTS : Linux kernel (Azure) vulnerabilities (USN-8243-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.130, 6.12.77, 6.18.18, 6.19.8 or 7.0-rc4 eliminates this vulnerability. Applying the patch 7c7cf05e0606f554c467e3a4dc49e2e578a755b4/76b4d36c5122866452d34d8f79985e191f9c3831/5a68e46dfe0c8c8ffc6f425ebc4cae6238566ecc/f39e126e56c6ec1930fae51ad6bca3dae2a4c3ed/d352873bbefa7eb39995239d0b44ccdf8aaa79a4 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 (314224), EUVD (EUVD-2026-17835) and CERT Bund (WID-SEC-2026-0950). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • Microsoft Azure 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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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: 314224
Nessus Name: Ubuntu 20.04 LTS : Linux kernel (Azure) vulnerabilities (USN-8243-1)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.130/6.12.77/6.18.18/6.19.8/7.0-rc4
Patch: 7c7cf05e0606f554c467e3a4dc49e2e578a755b4/76b4d36c5122866452d34d8f79985e191f9c3831/5a68e46dfe0c8c8ffc6f425ebc4cae6238566ecc/f39e126e56c6ec1930fae51ad6bca3dae2a4c3ed/d352873bbefa7eb39995239d0b44ccdf8aaa79a4

Timelineinfo

01/13/2026 CVE reserved
04/01/2026 +77 days Advisory disclosed
04/01/2026 +0 days VulDB entry created
07/01/2026 +91 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-23407 (🔒)
GCVE (CVE): GCVE-0-2026-23407
GCVE (VulDB): GCVE-100-354618
EUVD: 🔒
CERT Bund: WID-SEC-2026-0950 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 04/01/2026 11:24
Updated: 07/01/2026 14:50
Changes: 04/01/2026 11:24 (59), 04/01/2026 21:59 (7), 04/15/2026 07:03 (1), 04/19/2026 23:44 (1), 05/04/2026 06:41 (1), 05/12/2026 10:25 (2), 07/01/2026 14:50 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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