CVE-2026-23406

HIGHNVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-04-01. NVD baseline CVSS 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
7.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.8Exploit: None knownExposed: 0

A fix is available — apply it.

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

apparmor: fix side-effect bug in match_char() macro usage

The match_char() macro evaluates its character parameter multiple times when traversing differential encoding chains. When invoked with *str++, the string pointer advances on each iteration of the inner do-while loop, causing the DFA to check different characters at each iteration and therefore skip input characters. This results in out-of-bounds reads when the pointer advances past the input buffer boundary.

[ 94.984676] ================================================================== [ 94.985301] BUG: KASAN: slab-out-of-bounds in aa_dfa_match+0x5ae/0x760 [ 94.985655] Read of size 1 at addr ffff888100342000 by task file/976

[ 94.986319] CPU: 7 UID: 1000 PID: 976 Comm: file Not tainted 6.19.0-rc7-next-20260127 #1 PREEMPT(lazy) [ 94.986322] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 94.986329] Call Trace: [ 94.986341] [ 94.986347] dump_stack_lvl+0x5e/0x80 [ 94.986374] print_report+0xc8/0x270 [ 94.986384] ? aa_dfa_match+0x5ae/0x760 [ 94.986388] kasan_report+0x118/0x150 [ 94.986401] ? aa_dfa_match+0x5ae/0x760 [ 94.986405] aa_dfa_match+0x5ae/0x760 [ 94.986408] __aa_path_perm+0x131/0x400 [ 94.986418] aa_path_perm+0x219/0x2f0 [ 94.986424] apparmor_file_open+0x345/0x570 [ 94.986431] security_file_open+0x5c/0x140 [ 94.986442] do_dentry_open+0x2f6/0x1120 [ 94.986450] vfs_open+0x38/0x2b0 [ 94.986453] ? may_open+0x1e2/0x2b0 [ 94.986466] path_openat+0x231b/0x2b30 [ 94.986469] ? __x64_sys_openat+0xf8/0x130 [ 94.986477] do_file_open+0x19d/0x360 [ 94.986487] do_sys_openat2+0x98/0x100 [ 94.986491] __x64_sys_openat+0xf8/0x130 [ 94.986499] do_syscall_64+0x8e/0x660 [ 94.986515] ? count_memcg_events+0x15f/0x3c0 [ 94.986526] ? srso_alias_return_thunk+0x5/0xfbef5 [ 94.986540] ? handle_mm_fault+0x1639/0x1ef0 [ 94.986551] ? vma_start_read+0xf0/0x320 [ 94.986558] ? srso_alias_return_thunk+0x5/0xfbef5 [ 94.986561] ? srso_alias_return_thunk+0x5/0xfbef5 [ 94.986563] ? fpregs_assert_state_consistent+0x50/0xe0 [ 94.986572] ? srso_alias_return_thunk+0x5/0xfbef5 [ 94.986574] ? arch_exit_to_user_mode_prepare+0x9/0xb0 [ 94.986587] ? srso_alias_return_thunk+0x5/0xfbef5 [ 94.986588] ? irqentry_exit+0x3c/0x590 [ 94.986595] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 94.986597] RIP: 0033:0x7fda4a79c3ea

Fix by extracting the character value before invoking match_char, ensuring single evaluation per outer loop.

CVSS v3
7.8
EG Score
7.8(medium)
EG Risk
40(Track)
EG Risk 40/100SSVC: 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
Severity78% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
8%
KEV
Not listed

Published

April 1, 2026

Last Modified

April 24, 2026

Advisory Details (8)

Auto-updated Jun 10, 2026
No patch confirmed yet.
generic

apparmor: fix side-effect bug in match_char() macro usage - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/f16f2e5936c0f5f0d11fdf10d2be3e47e7108e42
generic

apparmor: fix side-effect bug in match_char() macro usage - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/c7dc56d8b37eda1396feeec3ab1c7ecee5eae31b
generic

apparmor: fix side-effect bug in match_char() macro usage - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/b73c1dff8a9d7eeaebabf8097a5b2de192f40913
generic

apparmor: fix side-effect bug in match_char() macro usage - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/8756b68edae37ff546c02091989a4ceab3f20abd
generic

apparmor: fix side-effect bug in match_char() macro usage - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/5a184f7cbdeaad17e16dedf3c17d0cd622edfed8
generic

apparmor: fix side-effect bug in match_char() macro usage - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/383b7270faf42564f133134c2fc3c24bbae52615
generic

apparmor: fix side-effect bug in match_char() macro usage - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/1fc94f16098213d01e56c97feed9b3ecf0147a37
generic

apparmor: fix side-effect bug in match_char() macro usage - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/0510d1ba0976f97f521feb2b75b0572ea5df3ceb

Vendor Advisories for CVE-2026-23406(1)

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

Patch Availability(11)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-tools-azure-fips-5.15 (5.15.0.1109.94) @ jammy2026-06-11ubuntu
ubuntulinux-tools-azure-lts-22.04 (5.15.0.1109.107) @ jammy2026-06-11ubuntu
ubuntulinux-xilinx-zynqmp (6.8.0.1029.30) @ noble2026-06-11ubuntu
ubuntulinux-tools-bluefield-5.4 (5.4.0.1116.112) @ focal2026-06-11ubuntu
ubuntulinux-tools-azure-edge (5.15.0.1110.119~20.04.1) @ focal2026-06-11ubuntu
ubuntulinux-tools-oem-6.17 (6.17.0-1017.17) @ noble2026-06-11ubuntu
ubuntulinux-tools-azure-edge (5.4.0.1161.167~18.04.1) @ bionic2026-06-11ubuntu
ubuntulinux-tools-intel-iot-realtime-5.15 (5.15.0.1096.100) @ jammy2026-06-11ubuntu
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
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.

Weakness Classification(1)

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

Additional Vendor Advisories

(10)

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 12× in last 7d / 48× 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 136 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-23406?
CVE-2026-23406 is a high vulnerability published on April 1, 2026. In the Linux kernel, the following vulnerability has been resolved: apparmor: fix side-effect bug in match_char() macro usage The match_char() macro evaluates its character parameter multiple times when traversing differential encoding chains. When invoked with *str++, the string pointer advances…
When was CVE-2026-23406 disclosed?
CVE-2026-23406 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-2026-23406 actively exploited?
CVE-2026-23406 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 92.5% of all scored CVEs.
What is the CVSS score of CVE-2026-23406?
CVE-2026-23406 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2026-23406?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-23406, 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

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