CVE-2026-23403

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
5.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.5Exploit: None knownExposed: 0

A fix is available — apply it.

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.

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
7%
KEV
Not listed

Published

April 1, 2026

Last Modified

April 24, 2026

Advisory Details (8)

Auto-updated Aug 6, 2026
No patch confirmed yet.
generic

apparmor: fix memory leak in verify_header - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/e38c55d9f834e5b848bfed0f5c586aaf45acb825
generic

apparmor: fix memory leak in verify_header - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/bcf82c0c5a8b383fd2d5d8f3fd880cdcab2ac557
generic

apparmor: fix memory leak in verify_header - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/9d678eb0fe55c9195d9a253e8c5b82a87b930737
generic

apparmor: fix memory leak in verify_header - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/786e2c2a87d9c505f33321d1fd23a176aa8ddeb1
generic

apparmor: fix memory leak in verify_header - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/6b79abcb3c985e153fcf9d395e1d4336081aabc2
generic

apparmor: fix memory leak in verify_header - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/663ce34786e759ebcbeb3060685c20bcc886d51a
generic

apparmor: fix memory leak in verify_header - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/4f0889f2df1ab99224a5e1ac4e20437eea5fe38e
generic

apparmor: fix memory leak in verify_header - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/42fd831abfc15d0643c14688f0522556b347e7e6

Vendor Advisories for CVE-2026-23403(1)

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

Patch Availability(13)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-tools-azure-fips-5.15 (5.15.0.1109.94) @ jammy2026-06-11ubuntu
ubuntulinux-tools-oem-6.17 (6.17.0-1017.17) @ noble2026-06-11ubuntu
ubuntulinux-tools-intel-iot-realtime-5.15 (5.15.0.1096.100) @ jammy2026-06-11ubuntu
ubuntulinux-tools-bluefield-5.4 (5.4.0.1116.112) @ focal2026-06-11ubuntu
ubuntulinux-xilinx-zynqmp (6.8.0.1029.30) @ noble2026-06-11ubuntu
ubuntulinux-tools-azure-edge (5.15.0.1110.119~20.04.1) @ focal2026-06-11ubuntu
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-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
ubuntulinux-virtual-hwe-16.04-edge (4.15.0.249.261~16.04.1) @ xenial2026-06-11ubuntu
ubuntulinux-tools-oracle (4.15.0.1153.164~16.04.1) @ xenial2026-06-11ubuntu
linuxKernel @ 5.10.253—osv

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.

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
linux5.10.103-1 ... 5.10.92-2 (49 versions)5.10.251-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
linux6.1.106-1 ... 6.1.99-1 (47 versions)6.1.164-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux6.12.38-1 ... 6.12.74-2~bpo12+1 (15 versions)6.12.74-2—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 6.19~rc8-1~exp1 (118 versions)6.19.6-2—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

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 5× in last 7d / 28× 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 203 total refreshes for this CVE.

  1. 2026-09-13 16:47 UTCEPSS rescore
  2. 2026-09-12 15:01 UTCEPSS rescore
  3. 2026-09-11 14:52 UTCEPSS rescore
  4. 2026-09-10 09:34 UTCEPSS rescore
  5. 2026-09-08 22:00 UTCEPSS rescore
  6. 2026-09-07 16:01 UTCEPSS rescore
  7. 2026-09-06 13:47 UTCEPSS rescore
  8. 2026-09-06 13:47 UTCEPSS rescore
  9. 2026-09-04 05:06 UTCEPSS rescore
  10. 2026-09-02 14:11 UTCEPSS rescore
  11. 2026-09-02 11:44 UTCOSV refresh
  12. 2026-09-01 13:53 UTCEPSS rescore
  13. 2026-09-01 04:39 UTCEPSS rescore
  14. 2026-08-30 19:17 UTCEPSS rescore
  15. 2026-08-30 01:22 UTCEPSS rescore
  16. 2026-08-28 21:41 UTCEPSS rescore
  17. 2026-08-27 14:25 UTCEPSS rescore
  18. 2026-08-26 14:46 UTCEPSS rescore
  19. 2026-08-23 00:19 UTCEPSS rescore
  20. 2026-08-21 23:49 UTCEPSS rescore
  21. 2026-08-20 22:55 UTCEPSS rescore
  22. 2026-08-19 17:03 UTCEPSS rescore
  23. 2026-08-18 13:48 UTCEPSS rescore
  24. 2026-08-17 13:47 UTCEPSS rescore
  25. 2026-08-16 14:56 UTCEPSS rescore
Show 75 more
  1. 2026-08-16 09:32 UTCEG score recompute
  2. 2026-08-16 09:32 UTCVendor advisory
  3. 2026-08-16 09:32 UTCGHSA enrichment
  4. 2026-08-16 02:14 UTCEPSS rescore
  5. 2026-08-15 01:30 UTCEPSS rescore
  6. 2026-08-14 05:57 UTCEG score recompute
  7. 2026-08-14 05:57 UTCVendor advisory
  8. 2026-08-14 05:57 UTCGHSA enrichment
  9. 2026-08-13 22:00 UTCEPSS rescore
  10. 2026-08-12 20:14 UTCEG score recompute
  11. 2026-08-12 20:14 UTCVendor advisory
  12. 2026-08-12 20:14 UTCGHSA enrichment
  13. 2026-08-12 13:50 UTCEPSS rescore
  14. 2026-08-11 13:42 UTCEPSS rescore
  15. 2026-08-11 09:13 UTCEG score recompute
  16. 2026-08-11 09:13 UTCVendor advisory
  17. 2026-08-11 09:12 UTCGHSA enrichment
  18. 2026-08-11 00:00 UTCEPSS rescore
  19. 2026-08-10 07:21 UTCEG score recompute
  20. 2026-08-10 07:21 UTCVendor advisory
  21. 2026-08-10 07:21 UTCGHSA enrichment
  22. 2026-08-09 13:46 UTCEPSS rescore
  23. 2026-08-09 05:31 UTCEG score recompute
  24. 2026-08-09 05:31 UTCVendor advisory
  25. 2026-08-09 05:31 UTCGHSA enrichment
  26. 2026-08-08 16:37 UTCEPSS rescore
  27. 2026-08-07 15:37 UTCEG score recompute
  28. 2026-08-07 15:37 UTCVendor advisory
  29. 2026-08-07 15:37 UTCGHSA enrichment
  30. 2026-08-06 13:46 UTCEPSS rescore
  31. 2026-08-06 00:31 UTCEG score recompute
  32. 2026-08-06 00:31 UTCVendor advisory
  33. 2026-08-06 00:31 UTCGHSA enrichment
  34. 2026-08-05 19:17 UTCEPSS rescore
  35. 2026-08-04 15:10 UTCEPSS rescore
  36. 2026-08-04 10:38 UTCEPSS rescore
  37. 2026-08-03 22:51 UTCEG score recompute
  38. 2026-08-03 22:51 UTCVendor advisory
  39. 2026-08-03 22:51 UTCGHSA enrichment
  40. 2026-08-03 10:35 UTCEPSS rescore
  41. 2026-08-02 14:51 UTCEG score recompute
  42. 2026-08-02 14:51 UTCVendor advisory
  43. 2026-08-02 14:51 UTCGHSA enrichment
  44. 2026-08-02 02:26 UTCEPSS rescore
  45. 2026-08-01 04:15 UTCEPSS rescore
  46. 2026-07-30 01:30 UTCEPSS rescore
  47. 2026-07-27 14:13 UTCEPSS rescore
  48. 2026-07-26 14:54 UTCEPSS rescore
  49. 2026-07-26 14:54 UTCEPSS rescore
  50. 2026-07-25 14:17 UTCEPSS rescore
  51. 2026-07-25 14:17 UTCEPSS rescore
  52. 2026-07-24 14:17 UTCEPSS rescore
  53. 2026-07-23 14:18 UTCEPSS rescore
  54. 2026-07-23 14:18 UTCEPSS rescore
  55. 2026-07-23 03:07 UTCEG score recompute
  56. 2026-07-22 14:08 UTCEPSS rescore
  57. 2026-07-21 15:24 UTCEPSS rescore
  58. 2026-07-21 15:24 UTCEPSS rescore
  59. 2026-07-20 17:08 UTCEPSS rescore
  60. 2026-07-19 14:31 UTCEPSS rescore
  61. 2026-07-19 14:31 UTCEPSS rescore
  62. 2026-07-19 02:29 UTCEPSS rescore
  63. 2026-07-19 02:28 UTCEPSS rescore
  64. 2026-07-18 10:04 UTCEPSS rescore
  65. 2026-07-18 10:04 UTCEPSS rescore
  66. 2026-07-17 04:24 UTCOSV refresh
  67. 2026-07-16 17:03 UTCEPSS rescore
  68. 2026-07-16 17:03 UTCEPSS rescore
  69. 2026-07-15 16:57 UTCEPSS rescore
  70. 2026-07-15 16:57 UTCEPSS rescore
  71. 2026-07-15 02:00 UTCEPSS rescore
  72. 2026-07-15 02:00 UTCEPSS rescore
  73. 2026-07-13 22:30 UTCEPSS rescore
  74. 2026-07-13 06:13 UTCEPSS rescore
  75. 2026-07-13 06:13 UTCEPSS rescore

Frequently asked(5)

What is CVE-2026-23403?
CVE-2026-23403 is a medium vulnerability published on April 1, 2026. 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…
When was CVE-2026-23403 disclosed?
CVE-2026-23403 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-2026-23403 actively exploited?
CVE-2026-23403 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 92.6% of all scored CVEs.
What is the CVSS score of CVE-2026-23403?
CVE-2026-23403 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2026-23403?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-23403, 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.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-23403

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