CVE-2026-23415 (GCVE-0-2026-23415)
Vulnerability from cvelistv5
Published
2026-04-02 11:40
Modified
2026-08-05 12:21
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: futex: Fix UaF between futex_key_to_node_opt() and vma_replace_policy() During futex_key_to_node_opt() execution, vma->vm_policy is read under speculative mmap lock and RCU. Concurrently, mbind() may call vma_replace_policy() which frees the old mempolicy immediately via kmem_cache_free(). This creates a race where __futex_key_to_node() dereferences a freed mempolicy pointer, causing a use-after-free read of mpol->mode. [ 151.412631] BUG: KASAN: slab-use-after-free in __futex_key_to_node (kernel/futex/core.c:349) [ 151.414046] Read of size 2 at addr ffff888001c49634 by task e/87 [ 151.415969] Call Trace: [ 151.416732] __asan_load2 (mm/kasan/generic.c:271) [ 151.416777] __futex_key_to_node (kernel/futex/core.c:349) [ 151.416822] get_futex_key (kernel/futex/core.c:374 kernel/futex/core.c:386 kernel/futex/core.c:593) Fix by adding rcu to __mpol_put().
References
Impacted products
Vendor Product Version
Linux Linux Version: c042c505210dc3453f378df432c10fff3d471bc5
Version: c042c505210dc3453f378df432c10fff3d471bc5
Version: c042c505210dc3453f378df432c10fff3d471bc5
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/linux/mempolicy.h",
            "kernel/futex/core.c",
            "mm/mempolicy.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "853f70c67d1b37e368fdcb3e328c4b8c04f53ac0",
              "status": "affected",
              "version": "c042c505210dc3453f378df432c10fff3d471bc5",
              "versionType": "git"
            },
            {
              "lessThan": "7e196194ea27bd49adf3551e2aceb83498eb73fe",
              "status": "affected",
              "version": "c042c505210dc3453f378df432c10fff3d471bc5",
              "versionType": "git"
            },
            {
              "lessThan": "190a8c48ff623c3d67cb295b4536a660db2012aa",
              "status": "affected",
              "version": "c042c505210dc3453f378df432c10fff3d471bc5",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/linux/mempolicy.h",
            "kernel/futex/core.c",
            "mm/mempolicy.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "lessThan": "6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.21",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.11",
              "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": "6.18.21",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.11",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Fix UaF between futex_key_to_node_opt() and vma_replace_policy()\n\nDuring futex_key_to_node_opt() execution, vma-\u003evm_policy is read under\nspeculative mmap lock and RCU. Concurrently, mbind() may call\nvma_replace_policy() which frees the old mempolicy immediately via\nkmem_cache_free().\n\nThis creates a race where __futex_key_to_node() dereferences a freed\nmempolicy pointer, causing a use-after-free read of mpol-\u003emode.\n\n[  151.412631] BUG: KASAN: slab-use-after-free in __futex_key_to_node (kernel/futex/core.c:349)\n[  151.414046] Read of size 2 at addr ffff888001c49634 by task e/87\n\n[  151.415969] Call Trace:\n\n[  151.416732]  __asan_load2 (mm/kasan/generic.c:271)\n[  151.416777]  __futex_key_to_node (kernel/futex/core.c:349)\n[  151.416822]  get_futex_key (kernel/futex/core.c:374 kernel/futex/core.c:386 kernel/futex/core.c:593)\n\nFix by adding rcu to __mpol_put()."
        }
      ],
      "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 vulnerable path is reached through local futex2/io_uring futex operations using FUTEX2_MPOL against the caller\u0027s user address space. It is not exposed directly to remote packets or adjacent/physical inputs.\nAC:L - The attacker can control both sides of the race by running concurrent threads that invoke futex wake/wait key derivation and mbind()/set_mempolicy_home_node() policy replacement on the same VMA. No external victim timing or rare state is required once the affected CONFIG_FUTEX_MPOL kernel is in use.\nPR:L - Both futex operations and basic mbind() VMA policy replacement are available to an unprivileged local user for their own process address space. The only relevant capability check is for MPOL_MF_MOVE_ALL, which is not needed to replace the VMA policy and trigger the UAF.\nUI:N - No victim action is required; the attacker can create the mapping, set policy, and issue the racing syscalls directly. Exploitation is self-contained in attacker-controlled local processes/threads.\nS:U - The bug is in the kernel\u0027s futex/mempolicy handling and affects the same kernel security authority. This is a standard local kernel vulnerability rather than a VM/IOMMU or separate-scope boundary crossing.\nC:H - This is a kernel use-after-free of struct mempolicy during futex key derivation, and UAF conditions can expose freed kernel heap contents or be shaped with heap reuse. Following the higher-severity rule for UAFs, confidentiality impact is High.\nI:H - The stale mempolicy data influences futex hash node selection and subsequent kernel data structure access, making memory corruption or control-flow-relevant exploitation defensible under UAF heap reuse. Following the higher-severity rule for UAFs, integrity impact is High.\nA:H - The reported failure is a KASAN slab-use-after-free in __futex_key_to_node(), and stale or invalid policy data can crash/oops the kernel. A local attacker can trigger the race repeatedly, so availability impact is High."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:21:35.941Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/853f70c67d1b37e368fdcb3e328c4b8c04f53ac0"
        },
        {
          "url": "https://git.kernel.org/stable/c/7e196194ea27bd49adf3551e2aceb83498eb73fe"
        },
        {
          "url": "https://git.kernel.org/stable/c/190a8c48ff623c3d67cb295b4536a660db2012aa"
        }
      ],
      "title": "futex: Fix UaF between futex_key_to_node_opt() and vma_replace_policy()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23415",
    "datePublished": "2026-04-02T11:40:56.476Z",
    "dateReserved": "2026-01-13T15:37:46.014Z",
    "dateUpdated": "2026-08-05T12:21:35.941Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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