Vulnerability-Lookup

FKIE_CVE-2026-23406

Vulnerability from fkie_nvd - Published: 2026-04-01 09:16 - Updated: 2026-06-17 10:21

Severity

7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Summary

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] <TASK> [ 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.

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/0510d1ba0976f97f521feb2b75b0572ea5df3ceb	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/1fc94f16098213d01e56c97feed9b3ecf0147a37	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/383b7270faf42564f133134c2fc3c24bbae52615	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/5a184f7cbdeaad17e16dedf3c17d0cd622edfed8	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/8756b68edae37ff546c02091989a4ceab3f20abd	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/b73c1dff8a9d7eeaebabf8097a5b2de192f40913	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/c7dc56d8b37eda1396feeec3ab1c7ecee5eae31b	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/f16f2e5936c0f5f0d11fdf10d2be3e47e7108e42	Patch

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	4.17
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0

JSON

To clipboard

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              "status": "unaffected",
              "version": "6.1.169",
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              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.130",
              "versionType": "semver"
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              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.77",
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              "lessThanOrEqual": "*",
              "status": "unaffected",
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\napparmor: fix side-effect bug in match_char() macro usage\n\nThe match_char() macro evaluates its character parameter multiple\ntimes when traversing differential encoding chains. When invoked\nwith *str++, the string pointer advances on each iteration of the\ninner do-while loop, causing the DFA to check different characters\nat each iteration and therefore skip input characters.\nThis results in out-of-bounds reads when the pointer advances past\nthe input buffer boundary.\n\n[   94.984676] ==================================================================\n[   94.985301] BUG: KASAN: slab-out-of-bounds in aa_dfa_match+0x5ae/0x760\n[   94.985655] Read of size 1 at addr ffff888100342000 by task file/976\n\n[   94.986319] CPU: 7 UID: 1000 PID: 976 Comm: file Not tainted 6.19.0-rc7-next-20260127 #1 PREEMPT(lazy)\n[   94.986322] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n[   94.986329] Call Trace:\n[   94.986341]  \u003cTASK\u003e\n[   94.986347]  dump_stack_lvl+0x5e/0x80\n[   94.986374]  print_report+0xc8/0x270\n[   94.986384]  ? aa_dfa_match+0x5ae/0x760\n[   94.986388]  kasan_report+0x118/0x150\n[   94.986401]  ? aa_dfa_match+0x5ae/0x760\n[   94.986405]  aa_dfa_match+0x5ae/0x760\n[   94.986408]  __aa_path_perm+0x131/0x400\n[   94.986418]  aa_path_perm+0x219/0x2f0\n[   94.986424]  apparmor_file_open+0x345/0x570\n[   94.986431]  security_file_open+0x5c/0x140\n[   94.986442]  do_dentry_open+0x2f6/0x1120\n[   94.986450]  vfs_open+0x38/0x2b0\n[   94.986453]  ? may_open+0x1e2/0x2b0\n[   94.986466]  path_openat+0x231b/0x2b30\n[   94.986469]  ? __x64_sys_openat+0xf8/0x130\n[   94.986477]  do_file_open+0x19d/0x360\n[   94.986487]  do_sys_openat2+0x98/0x100\n[   94.986491]  __x64_sys_openat+0xf8/0x130\n[   94.986499]  do_syscall_64+0x8e/0x660\n[   94.986515]  ? count_memcg_events+0x15f/0x3c0\n[   94.986526]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   94.986540]  ? handle_mm_fault+0x1639/0x1ef0\n[   94.986551]  ? vma_start_read+0xf0/0x320\n[   94.986558]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   94.986561]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   94.986563]  ? fpregs_assert_state_consistent+0x50/0xe0\n[   94.986572]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   94.986574]  ? arch_exit_to_user_mode_prepare+0x9/0xb0\n[   94.986587]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   94.986588]  ? irqentry_exit+0x3c/0x590\n[   94.986595]  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n[   94.986597] RIP: 0033:0x7fda4a79c3ea\n\nFix by extracting the character value before invoking match_char,\nensuring single evaluation per outer loop."
    }
  ],
  "id": "CVE-2026-23406",
  "lastModified": "2026-06-17T10:21:31.200",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-04-01T09:16:16.327",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/0510d1ba0976f97f521feb2b75b0572ea5df3ceb"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/1fc94f16098213d01e56c97feed9b3ecf0147a37"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/383b7270faf42564f133134c2fc3c24bbae52615"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/5a184f7cbdeaad17e16dedf3c17d0cd622edfed8"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/8756b68edae37ff546c02091989a4ceab3f20abd"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/b73c1dff8a9d7eeaebabf8097a5b2de192f40913"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/c7dc56d8b37eda1396feeec3ab1c7ecee5eae31b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/f16f2e5936c0f5f0d11fdf10d2be3e47e7108e42"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-125"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

CVE-2026-23406 (GCVE-0-2026-23406)

Vulnerability from cvelistv5 – Published: 2026-04-01 08:36 – Updated: 2026-08-05 12:21

Title

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

Summary

Severity

7.8 (High)


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

Assigner

Linux mitre root

References

8 references

URL	Tags
https://git.kernel.org/stable/c/c7dc56d8b37eda139…
https://git.kernel.org/stable/c/f16f2e5936c0f5f0d…
https://git.kernel.org/stable/c/1fc94f16098213d01…
https://git.kernel.org/stable/c/5a184f7cbdeaad17e…
https://git.kernel.org/stable/c/b73c1dff8a9d7eeae…
https://git.kernel.org/stable/c/0510d1ba0976f97f5…
https://git.kernel.org/stable/c/383b7270faf42564f…
https://git.kernel.org/stable/c/8756b68edae37ff54…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 074c1cd798cb0b481d7eaa749b64aa416563c053 , < c7dc56d8b37eda1396feeec3ab1c7ecee5eae31b (git) Affected: 074c1cd798cb0b481d7eaa749b64aa416563c053 , < f16f2e5936c0f5f0d11fdf10d2be3e47e7108e42 (git) Affected: 074c1cd798cb0b481d7eaa749b64aa416563c053 , < 1fc94f16098213d01e56c97feed9b3ecf0147a37 (git) Affected: 074c1cd798cb0b481d7eaa749b64aa416563c053 , < 5a184f7cbdeaad17e16dedf3c17d0cd622edfed8 (git) Affected: 074c1cd798cb0b481d7eaa749b64aa416563c053 , < b73c1dff8a9d7eeaebabf8097a5b2de192f40913 (git) Affected: 074c1cd798cb0b481d7eaa749b64aa416563c053 , < 0510d1ba0976f97f521feb2b75b0572ea5df3ceb (git) Affected: 074c1cd798cb0b481d7eaa749b64aa416563c053 , < 383b7270faf42564f133134c2fc3c24bbae52615 (git) Affected: 074c1cd798cb0b481d7eaa749b64aa416563c053 , < 8756b68edae37ff546c02091989a4ceab3f20abd (git)
Linux	Linux	Affected: 4.17 Unaffected: 0 , < 4.17 (semver) Unaffected: 5.10.253 , ≤ 5.10.* (semver) Unaffected: 5.15.203 , ≤ 5.15.* (semver) Unaffected: 6.1.169 , ≤ 6.1.* (semver) Unaffected: 6.6.130 , ≤ 6.6.* (semver) Unaffected: 6.12.77 , ≤ 6.12.* (semver) Unaffected: 6.18.18 , ≤ 6.18.* (semver) Unaffected: 6.19.8 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "security/apparmor/match.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c7dc56d8b37eda1396feeec3ab1c7ecee5eae31b",
              "status": "affected",
              "version": "074c1cd798cb0b481d7eaa749b64aa416563c053",
              "versionType": "git"
            },
            {
              "lessThan": "f16f2e5936c0f5f0d11fdf10d2be3e47e7108e42",
              "status": "affected",
              "version": "074c1cd798cb0b481d7eaa749b64aa416563c053",
              "versionType": "git"
            },
            {
              "lessThan": "1fc94f16098213d01e56c97feed9b3ecf0147a37",
              "status": "affected",
              "version": "074c1cd798cb0b481d7eaa749b64aa416563c053",
              "versionType": "git"
            },
            {
              "lessThan": "5a184f7cbdeaad17e16dedf3c17d0cd622edfed8",
              "status": "affected",
              "version": "074c1cd798cb0b481d7eaa749b64aa416563c053",
              "versionType": "git"
            },
            {
              "lessThan": "b73c1dff8a9d7eeaebabf8097a5b2de192f40913",
              "status": "affected",
              "version": "074c1cd798cb0b481d7eaa749b64aa416563c053",
              "versionType": "git"
            },
            {
              "lessThan": "0510d1ba0976f97f521feb2b75b0572ea5df3ceb",
              "status": "affected",
              "version": "074c1cd798cb0b481d7eaa749b64aa416563c053",
              "versionType": "git"
            },
            {
              "lessThan": "383b7270faf42564f133134c2fc3c24bbae52615",
              "status": "affected",
              "version": "074c1cd798cb0b481d7eaa749b64aa416563c053",
              "versionType": "git"
            },
            {
              "lessThan": "8756b68edae37ff546c02091989a4ceab3f20abd",
              "status": "affected",
              "version": "074c1cd798cb0b481d7eaa749b64aa416563c053",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "security/apparmor/match.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.17"
            },
            {
              "lessThan": "4.17",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.253",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.203",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.169",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.130",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.77",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.18",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.253",
                  "versionStartIncluding": "4.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.203",
                  "versionStartIncluding": "4.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.169",
                  "versionStartIncluding": "4.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.130",
                  "versionStartIncluding": "4.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.77",
                  "versionStartIncluding": "4.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.18",
                  "versionStartIncluding": "4.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.8",
                  "versionStartIncluding": "4.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "4.17",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\napparmor: fix side-effect bug in match_char() macro usage\n\nThe match_char() macro evaluates its character parameter multiple\ntimes when traversing differential encoding chains. When invoked\nwith *str++, the string pointer advances on each iteration of the\ninner do-while loop, causing the DFA to check different characters\nat each iteration and therefore skip input characters.\nThis results in out-of-bounds reads when the pointer advances past\nthe input buffer boundary.\n\n[   94.984676] ==================================================================\n[   94.985301] BUG: KASAN: slab-out-of-bounds in aa_dfa_match+0x5ae/0x760\n[   94.985655] Read of size 1 at addr ffff888100342000 by task file/976\n\n[   94.986319] CPU: 7 UID: 1000 PID: 976 Comm: file Not tainted 6.19.0-rc7-next-20260127 #1 PREEMPT(lazy)\n[   94.986322] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n[   94.986329] Call Trace:\n[   94.986341]  \u003cTASK\u003e\n[   94.986347]  dump_stack_lvl+0x5e/0x80\n[   94.986374]  print_report+0xc8/0x270\n[   94.986384]  ? aa_dfa_match+0x5ae/0x760\n[   94.986388]  kasan_report+0x118/0x150\n[   94.986401]  ? aa_dfa_match+0x5ae/0x760\n[   94.986405]  aa_dfa_match+0x5ae/0x760\n[   94.986408]  __aa_path_perm+0x131/0x400\n[   94.986418]  aa_path_perm+0x219/0x2f0\n[   94.986424]  apparmor_file_open+0x345/0x570\n[   94.986431]  security_file_open+0x5c/0x140\n[   94.986442]  do_dentry_open+0x2f6/0x1120\n[   94.986450]  vfs_open+0x38/0x2b0\n[   94.986453]  ? may_open+0x1e2/0x2b0\n[   94.986466]  path_openat+0x231b/0x2b30\n[   94.986469]  ? __x64_sys_openat+0xf8/0x130\n[   94.986477]  do_file_open+0x19d/0x360\n[   94.986487]  do_sys_openat2+0x98/0x100\n[   94.986491]  __x64_sys_openat+0xf8/0x130\n[   94.986499]  do_syscall_64+0x8e/0x660\n[   94.986515]  ? count_memcg_events+0x15f/0x3c0\n[   94.986526]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   94.986540]  ? handle_mm_fault+0x1639/0x1ef0\n[   94.986551]  ? vma_start_read+0xf0/0x320\n[   94.986558]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   94.986561]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   94.986563]  ? fpregs_assert_state_consistent+0x50/0xe0\n[   94.986572]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   94.986574]  ? arch_exit_to_user_mode_prepare+0x9/0xb0\n[   94.986587]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   94.986588]  ? irqentry_exit+0x3c/0x590\n[   94.986595]  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n[   94.986597] RIP: 0033:0x7fda4a79c3ea\n\nFix by extracting the character value before invoking match_char,\nensuring single evaluation per outer loop."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerability is triggered through the file open syscall (openat) which goes through AppArmor\u0027s DFA matching on file paths. This requires local system access.\nAC:L - The bug is deterministic \u2014 any file path that triggers a differential encoding chain traversal in the AppArmor DFA will cause character skipping and OOB reads. The attacker reliably triggers it by opening files on systems with standard AppArmor policies using differential encoding.\nPR:L - Any unprivileged local user confined by an AppArmor profile can trigger this by performing normal file operations (e.g., opening files). No special privileges are required.\nUI:N - No user interaction is needed. The attacker simply opens files, and AppArmor\u0027s DFA matching is triggered automatically as part of the security hook.\nS:U - The vulnerability is in the kernel\u0027s AppArmor security module and impacts kernel memory and kernel-enforced access control, all within the same security authority (kernel space).\nC:H - The OOB read accesses kernel slab memory past the input buffer boundary, potentially reading unbounded amounts of adjacent kernel heap data. While the data is used as DFA indices rather than returned directly, the permission decision outcome can serve as an oracle.\nI:H - The incorrect DFA matching (skipping input characters) causes AppArmor to evaluate the wrong path against policy rules, potentially allowing file access that should be denied \u2014 effectively a mandatory access control policy bypass.\nA:H - The OOB read can advance the pointer past the slab allocation and potentially into unmapped memory, causing a kernel crash as demonstrated by the KASAN slab-out-of-bounds report in the commit message."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:21:26.927Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/c7dc56d8b37eda1396feeec3ab1c7ecee5eae31b"
        },
        {
          "url": "https://git.kernel.org/stable/c/f16f2e5936c0f5f0d11fdf10d2be3e47e7108e42"
        },
        {
          "url": "https://git.kernel.org/stable/c/1fc94f16098213d01e56c97feed9b3ecf0147a37"
        },
        {
          "url": "https://git.kernel.org/stable/c/5a184f7cbdeaad17e16dedf3c17d0cd622edfed8"
        },
        {
          "url": "https://git.kernel.org/stable/c/b73c1dff8a9d7eeaebabf8097a5b2de192f40913"
        },
        {
          "url": "https://git.kernel.org/stable/c/0510d1ba0976f97f521feb2b75b0572ea5df3ceb"
        },
        {
          "url": "https://git.kernel.org/stable/c/383b7270faf42564f133134c2fc3c24bbae52615"
        },
        {
          "url": "https://git.kernel.org/stable/c/8756b68edae37ff546c02091989a4ceab3f20abd"
        }
      ],
      "title": "apparmor: fix side-effect bug in match_char() macro usage",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23406",
    "datePublished": "2026-04-01T08:36:36.460Z",
    "dateReserved": "2026-01-13T15:37:46.013Z",
    "dateUpdated": "2026-08-05T12:21:26.927Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.