CVE-2026-23405

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2026-04-01. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.5Exploit: NoneExposed: 0

A fix is available — apply it.

In the Linux kernel, the following vulnerability has been resolved:

apparmor: fix: limit the number of levels of policy namespaces

Currently the number of policy namespaces is not bounded relying on the user namespace limit. However policy namespaces aren't strictly tied to user namespaces and it is possible to create them and nest them arbitrarily deep which can be used to exhaust system resource.

Hard cap policy namespaces to the same depth as user namespaces.

CVSS v3
5.5
EG Score
5.5(medium)
EPSS
7.8%
KEV
Not listed

Published

April 1, 2026

Last Modified

April 24, 2026

References (8)

Vendor Advisories for CVE-2026-23405(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(12)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-tools-oem-6.17 (6.17.0-1017.17) @ noble2026-06-11ubuntu
ubuntulinux-tools-azure-lts-22.04 (5.15.0.1109.107) @ jammy2026-06-11ubuntu
ubuntulinux-tools-azure-edge (5.4.0.1161.167~18.04.1) @ bionic2026-06-11ubuntu
ubuntulinux-tools-bluefield-5.4 (5.4.0.1116.112) @ focal2026-06-11ubuntu
ubuntulinux-tools-intel-iot-realtime-5.15 (5.15.0.1096.100) @ jammy2026-06-11ubuntu
ubuntulinux-tools-azure-edge (5.15.0.1110.119~20.04.1) @ focal2026-06-11ubuntu
ubuntulinux-xilinx-zynqmp (6.8.0.1029.30) @ noble2026-06-11ubuntu
ubuntulinux-tools-azure-fips-5.15 (5.15.0.1109.94) @ jammy2026-06-11ubuntu
ubuntulinux-tools-oracle (4.15.0.1153.164~16.04.1) @ xenial2026-06-11ubuntu
ubuntulinux-virtual-hwe-16.04-edge (4.15.0.249.233) @ bionic2026-06-11ubuntu
ubuntulinux-tools-azure-fips-6.8 (6.8.0-1052.58+fips1) @ noble2026-06-11ubuntu
ubuntulinux-tools-raspi2-hwe-18.04-edge (5.4.0.1139.170) @ focal2026-06-11ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Additional Vendor Advisories

(12)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 11× in last 7d / 45× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 111 total refreshes for this CVE.

  1. 2026-07-15 16:57 UTCEPSS rescore
  2. 2026-07-15 16:57 UTCEPSS rescore
  3. 2026-07-15 02:00 UTCEPSS rescore
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  10. 2026-07-11 08:27 UTCEPSS rescore
  11. 2026-07-09 19:10 UTCEPSS rescore
  12. 2026-07-08 15:15 UTCEPSS rescore
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  1. 2026-06-28 04:56 UTCEPSS rescore
  2. 2026-06-27 03:08 UTCEPSS rescore
  3. 2026-06-25 13:49 UTCEPSS rescore
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  5. 2026-06-24 14:05 UTCEPSS rescore
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  7. 2026-06-23 21:33 UTCEPSS rescore
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  9. 2026-06-22 14:25 UTCEPSS rescore
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  11. 2026-06-21 14:56 UTCEPSS rescore
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  21. 2026-06-15 17:48 UTCEPSS rescore
  22. 2026-06-14 23:18 UTCEPSS rescore
  23. 2026-06-13 23:00 UTCEPSS rescore
  24. 2026-06-12 23:12 UTCEPSS rescore
  25. 2026-06-12 23:12 UTCEPSS rescore
  26. 2026-06-11 22:27 UTCEG score recompute
  27. 2026-06-11 22:27 UTCVendor advisory
  28. 2026-06-11 22:27 UTCGHSA enrichment
  29. 2026-06-11 14:00 UTCEPSS rescore
  30. 2026-06-10 22:18 UTCEPSS rescore
  31. 2026-06-10 14:00 UTCEG score recompute
  32. 2026-06-10 14:00 UTCVendor advisory
  33. 2026-06-10 14:00 UTCGHSA enrichment
  34. 2026-06-10 13:22 UTCEPSS rescore
  35. 2026-06-09 14:55 UTCEG score recompute
  36. 2026-06-09 14:55 UTCVendor advisory
  37. 2026-06-09 14:55 UTCGHSA enrichment
  38. 2026-06-08 14:17 UTCEPSS rescore
  39. 2026-06-08 14:17 UTCEPSS rescore
  40. 2026-06-08 09:41 UTCEG score recompute
  41. 2026-06-08 09:41 UTCVendor advisory
  42. 2026-06-08 09:41 UTCGHSA enrichment
  43. 2026-06-07 15:25 UTCEPSS rescore
  44. 2026-06-07 15:24 UTCEPSS rescore
  45. 2026-06-07 11:20 UTCEG score recompute
  46. 2026-06-07 11:20 UTCVendor advisory
  47. 2026-06-07 11:20 UTCGHSA enrichment
  48. 2026-06-06 13:47 UTCEPSS rescore
  49. 2026-06-06 13:47 UTCEPSS rescore
  50. 2026-06-06 13:47 UTCEPSS rescore
  51. 2026-06-05 22:47 UTCEPSS rescore
  52. 2026-06-05 06:10 UTCEPSS rescore
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  54. 2026-06-04 13:12 UTCEPSS rescore
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  59. 2026-06-01 13:51 UTCEPSS rescore
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  62. 2026-05-31 22:30 UTCEPSS rescore
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  75. 2026-05-22 21:16 UTCEPSS rescore

Frequently asked(5)

What is CVE-2026-23405?
CVE-2026-23405 is a medium vulnerability published on April 1, 2026. In the Linux kernel, the following vulnerability has been resolved: apparmor: fix: limit the number of levels of policy namespaces Currently the number of policy namespaces is not bounded relying on the user namespace limit. However policy namespaces aren't strictly tied to user namespaces and it…
When was CVE-2026-23405 disclosed?
CVE-2026-23405 was first published in the National Vulnerability Database on April 1, 2026, with the most recent update on April 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-23405 actively exploited?
CVE-2026-23405 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 7.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-23405?
CVE-2026-23405 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2026-23405?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-23405, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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