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NVD / CVE Program· CNA Linux

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

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.18% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 22094c996968a7c5b59cd3fc9fcbdfdd46d02fec, 555829fd91eaf0711e369b0a92aecb0f0aa3281f, 5a68e46dfe0c8c8ffc6f425ebc4cae6238566ecc; azl3 kernel 6.6.0.0-1 on Azure Linux 3.0 6.6.130.1-1; cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0 Release Notes.

Low priority for now. Upgrade to Linux Linux 22094c996968a7c5b59cd3fc9fcbdfdd46d02fec, 555829fd91eaf0711e369b0a92aecb0f0aa3281f, 5a68e46dfe0c8c8ffc6f425ebc4cae6238566ecc; azl3 kernel 6.6.0.0-1 on Azure Linux 3.0 6.6.130.1-1; cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0 Release Notes or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Apr 1, 2026
Updated
Aug 5, 2026
EPSS
0.1% · 8th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CNA vs NVD score

NVD
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Follow CVE-2026-23407

When you'll hear from us

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel4.17.1 and later · before 5.10.253
  • linux linux kernel5.11 and later · before 5.15.203
  • linux linux kernel5.16 and later · before 6.1.169
  • linux linux kernel6.2 and later · before 6.6.130
  • linux linux kernel6.7 and later · before 6.12.77
  • linux linux kernel6.13 and later · before 6.18.18
  • linux linux kernel6.19 and later · before 6.19.8
  • linux linux kernel4.17
  • linux linux kernel7.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 4.17affected
    • 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 and later · before 555829fd91eaf0711e369b0a92aecb0f0aa3281faffected · git
    • 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 and later · before a75e12ca90c9e70ba10fee1be2f63cdd63d91a7caffected · git
    • 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 and later · before 22094c996968a7c5b59cd3fc9fcbdfdd46d02fecaffected · git
    • 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 and later · before 7c7cf05e0606f554c467e3a4dc49e2e578a755b4affected · git
    • 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 and later · before 76b4d36c5122866452d34d8f79985e191f9c3831affected · git
    • 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 and later · before 5a68e46dfe0c8c8ffc6f425ebc4cae6238566eccaffected · git
    • 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 and later · before f39e126e56c6ec1930fae51ad6bca3dae2a4c3edaffected · git
    • 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 and later · before d352873bbefa7eb39995239d0b44ccdf8aaa79a4affected · git
    • before 4.17not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.164-16.1.164-1
Debian:13linuxbefore 6.12.74-26.12.74-2
Debian:14linuxbefore 6.19.6-26.19.6-2
SUSE:Linux Enterprise Live Patching 15 SP6kernel-defaultbefore 6.4.0-150600.23.112.16.4.0-150600.23.112.1
SUSE:Linux Enterprise Live Patching 15 SP6kernel-livepatch-SLE15-SP6_Update_26before 1-150600.13.3.11-150600.13.3.1
SUSE:Linux Enterprise Server 15 SP6-LTSSkernel-64kbbefore 6.4.0-150600.23.112.16.4.0-150600.23.112.1
SUSE:Linux Enterprise Server 15 SP6-LTSSkernel-default-basebefore 6.4.0-150600.23.112.1.150600.12.52.16.4.0-150600.23.112.1.150600.12.52.1
SUSE:Linux Enterprise Server 15 SP6-LTSSkernel-docsbefore 6.4.0-150600.23.112.16.4.0-150600.23.112.1
SUSE:Linux Enterprise Server 15 SP6-LTSSkernel-obs-buildbefore 6.4.0-150600.23.112.16.4.0-150600.23.112.1
SUSE:Linux Enterprise Server 15 SP6-LTSSkernel-sourcebefore 6.4.0-150600.23.112.16.4.0-150600.23.112.1
SUSE:Linux Enterprise Server 15 SP6-LTSSkernel-symsbefore 6.4.0-150600.23.112.16.4.0-150600.23.112.1
SUSE:Linux Enterprise Server 15 SP6-LTSSkernel-zfcpdumpbefore 6.4.0-150600.23.112.16.4.0-150600.23.112.1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-23405Apr 1, 2026 · apparmor: fix: limit the number of levels of policy namespaces
    22Monitor
  • ← EarlierCVE-2026-23406Apr 1, 2026 · apparmor: fix side-effect bug in match_char() macro usage
    31Monitor
  • Later →CVE-2026-23408Apr 1, 2026 · apparmor: Fix double free of ns_name in aa_replace_profiles()
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux22094c996968a7c5b59cd3fc9fcbdfdd46d02fecVendor (CNA)
Linux Linux555829fd91eaf0711e369b0a92aecb0f0aa3281fVendor (CNA)
Linux Linux5a68e46dfe0c8c8ffc6f425ebc4cae6238566eccVendor (CNA)
Linux Linux76b4d36c5122866452d34d8f79985e191f9c3831Vendor (CNA)
Linux Linux7c7cf05e0606f554c467e3a4dc49e2e578a755b4Vendor (CNA)
Linux Linuxa75e12ca90c9e70ba10fee1be2f63cdd63d91a7cVendor (CNA)
Linux Linuxd352873bbefa7eb39995239d0b44ccdf8aaa79a4Vendor (CNA)
Linux Linuxf39e126e56c6ec1930fae51ad6bca3dae2a4c3edVendor (CNA)
azl3 kernel 6.6.0.0-1 on Azure Linux 3.06.6.130.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0Release NotesMicrosoft (MSRC)
debian:linux6.1.164-1 · Debian:12Package registry (OSV)
suse:kernel-64kb6.4.0-150600.23.112.1 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)
suse:kernel-default6.4.0-150600.23.112.1 · SUSE:Linux Enterprise Live Patching 15 SP6Package registry (OSV)
suse:kernel-default-base6.4.0-150600.23.112.1.150600.12.52.1 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)
suse:kernel-docs6.4.0-150600.23.112.1 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)
suse:kernel-livepatch-SLE15-SP6_Update_261-150600.13.3.1 · SUSE:Linux Enterprise Live Patching 15 SP6Package registry (OSV)
suse:kernel-obs-build6.4.0-150600.23.112.1 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)
suse:kernel-source6.4.0-150600.23.112.1 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)
suse:kernel-syms6.4.0-150600.23.112.1 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)
suse:kernel-zfcpdump6.4.0-150600.23.112.1 · SUSE:Linux Enterprise Server 15 SP6-LTSSPackage registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records