{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "317460317a02a1af512697e6e964298dedd8a163"
            },
            {
              "fixed": "723b9fa930cc277c15ce6b9ec9feec828cfac9d7"
            },
            {
              "fixed": "d18099f19e53250f8ad2801498b88cec29d9107a"
            },
            {
              "fixed": "201128fcc7b213d27ab77bc4e89488b41796480f"
            },
            {
              "fixed": "4fddde2a732de60bb97e3307d4eb69ac5f1d2b74"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.9.0"
            },
            {
              "fixed": "6.12.88"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.30"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.0.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45837.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix use-after-free in arena_vm_close on fork\n\narena_vm_open() only bumps vml-\u003emmap_count but never registers the\nchild VMA in arena-\u003evma_list. The vml-\u003evma always points at the\nparent VMA, so after parent munmap the pointer dangles. If the child\nthen calls bpf_arena_free_pages(), zap_pages() reads the stale\nvml-\u003evma triggering use-after-free.\n\nFix this by preventing the arena VMA from being inherited across\nfork with VM_DONTCOPY, and preventing VMA splits via the may_split\ncallback.\n\nAlso reject mremap with a .mremap callback returning -EINVAL. A\nsame-size mremap(MREMAP_FIXED) on the full arena VMA reaches\ncopy_vma() through the following path:\n\n  check_prep_vma()       - returns 0 early: new_len == old_len\n                           skips VM_DONTEXPAND check\n  prep_move_vma()        - vm_start == old_addr and\n                           vm_end == old_addr + old_len\n                           so may_split is never called\n  move_vma()\n    copy_vma_and_data()\n      copy_vma()\n        vm_area_dup()    - copies vm_private_data (vml pointer)\n        vm_ops-\u003eopen()   - bumps vml-\u003emmap_count\n      vm_ops-\u003emremap()   - returns -EINVAL, rollback unmaps new VMA\n\nThe refcount ensures the rollback's arena_vm_close does not free\nthe vml shared with the original VMA.",
  "id": "CVE-2026-45837",
  "modified": "2026-07-08T05:37:48.660987291Z",
  "published": "2026-05-27T09:24:32.833Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/201128fcc7b213d27ab77bc4e89488b41796480f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4fddde2a732de60bb97e3307d4eb69ac5f1d2b74"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/723b9fa930cc277c15ce6b9ec9feec828cfac9d7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d18099f19e53250f8ad2801498b88cec29d9107a"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45837.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45837"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.7.5",
  "summary": "bpf: Fix use-after-free in arena_vm_close on fork"
}