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NVD / CVE Program· CNA Linux

CVE-2026-23403: apparmor: fix memory leak in verify_header

Noroxi assessment

Priority: Monitor (action score 22/100)

  • 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: 0.17% (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 42fd831abfc15d0643c14688f0522556b347e7e6, 4f0889f2df1ab99224a5e1ac4e20437eea5fe38e, 663ce34786e759ebcbeb3060685c20bcc886d51a; azl3 kernel 0.0.0-1 on Azure Linux 3.0 6.6.130.1-1.

Low priority for now. Upgrade to Linux Linux 42fd831abfc15d0643c14688f0522556b347e7e6, 4f0889f2df1ab99224a5e1ac4e20437eea5fe38e, 663ce34786e759ebcbeb3060685c20bcc886d51a; azl3 kernel 0.0.0-1 on Azure Linux 3.0 6.6.130.1-1 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 memory leak in verify_header The function sets `*ns = NULL` on every call, leaking the namespace string allocated in previous iterations when multiple profiles are unpacked. This also breaks namespace consistency checking since *ns is always NULL when the comparison is made. Remove the incorrect assignment. The caller (aa_unpack) initializes *ns to NULL once before the loop, which is sufficient.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Apr 1, 2026
Updated
Jun 17, 2026
EPSS
0.1% · 7th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-23403

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • 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 kernel3.12.1 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 kernel3.12
  • 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

    • 3.12affected
    • dd51c84857630e77c139afe4d9bba65fc051dc3f and later · before 9d678eb0fe55c9195d9a253e8c5b82a87b930737affected · git
    • dd51c84857630e77c139afe4d9bba65fc051dc3f and later · before 6b79abcb3c985e153fcf9d395e1d4336081aabc2affected · git
    • dd51c84857630e77c139afe4d9bba65fc051dc3f and later · before bcf82c0c5a8b383fd2d5d8f3fd880cdcab2ac557affected · git
    • dd51c84857630e77c139afe4d9bba65fc051dc3f and later · before 663ce34786e759ebcbeb3060685c20bcc886d51aaffected · git
    • dd51c84857630e77c139afe4d9bba65fc051dc3f and later · before 786e2c2a87d9c505f33321d1fd23a176aa8ddeb1affected · git
    • dd51c84857630e77c139afe4d9bba65fc051dc3f and later · before 4f0889f2df1ab99224a5e1ac4e20437eea5fe38eaffected · git
    • dd51c84857630e77c139afe4d9bba65fc051dc3f and later · before 42fd831abfc15d0643c14688f0522556b347e7e6affected · git
    • dd51c84857630e77c139afe4d9bba65fc051dc3f and later · before e38c55d9f834e5b848bfed0f5c586aaf45acb825affected · git
    • before 3.12not 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-2026-23401Apr 1, 2026 · KVM: x86/mmu: Drop/zap existing present SPTE even when creating an MMIO SPTE
    22Monitor
  • ← EarlierCVE-2026-23402Apr 1, 2026 · KVM: x86/mmu: Only WARN in direct MMUs when overwriting shadow-present SPTE
    22Monitor
  • Later →CVE-2026-23404Apr 1, 2026 · apparmor: replace recursive profile removal with iterative approach
    22Monitor

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 Linux42fd831abfc15d0643c14688f0522556b347e7e6Vendor (CNA)
Linux Linux4f0889f2df1ab99224a5e1ac4e20437eea5fe38eVendor (CNA)
Linux Linux663ce34786e759ebcbeb3060685c20bcc886d51aVendor (CNA)
Linux Linux6b79abcb3c985e153fcf9d395e1d4336081aabc2Vendor (CNA)
Linux Linux786e2c2a87d9c505f33321d1fd23a176aa8ddeb1Vendor (CNA)
Linux Linux9d678eb0fe55c9195d9a253e8c5b82a87b930737Vendor (CNA)
Linux Linuxbcf82c0c5a8b383fd2d5d8f3fd880cdcab2ac557Vendor (CNA)
Linux Linuxe38c55d9f834e5b848bfed0f5c586aaf45acb825Vendor (CNA)
azl3 kernel 0.0.0-1 on Azure Linux 3.06.6.130.1-1 · CBL-Mariner ReleasesMicrosoft (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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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

Weakness class (CWE)

CWE-401 · Missing Release of Memory after Effective Lifetime

CVSS vector

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

nvd-primary

Attack context

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

MITRE has no CAPEC/ATT&CK mapping for this CWE.

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