CVE-2026-68187

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: exec: fix unsigned loop counter wrap in transfer_args_to_stack() The stop value is derived from bprm->p >> PAGE_SHIFT. The index variable is an unsigned long. If bprm->p drops below PAGE_SIZE and stop becomes zero the loop condition index >= stop is always true. After the index == 0 iteration the decrement wraps to ULONG_MAX and bprm->page[ULONG_MAX] reads sizeof(void *) bytes in front of the array. The pointer has wrapped to -1. That garbage pointer is then passed to kmap_local_page() and PAGE_SIZE bytes are copied from wherever that lands into the stack of the process being created. And the loop doesn't terminate either... Getting there only requires bprm->p < PAGE_SIZE. On !MMU bprm_set_stack_limit() and bprm_hit_stack_limit() are empty. So the only constraint on how far bprm->p is pushed down is valid_arg_len(), i.e. that each individual string still fits in what is left. bprm->p starts at PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *) so a single argument or environment string of a little over 31 pages leaves it in the first page: Oops - load access fault [#1] CPU: 0 UID: 0 PID: 1 Comm: victim Not tainted 7.2.0-rc4 #1 epc : __memcpy+0xd4/0xf8 ra : transfer_args_to_stack+0xaa/0xae s4 : ffffffffffffffff s2 : 0000000000000000 a1 : ffffffdc98000000 a2 : 0000000000001000 status: 0000000a00001880 badaddr: ffffffdc98000000 cause: 0000000000000005 [<801a5324>] __memcpy+0xd4/0xf8 [<800d5f6a>] load_flat_binary+0x43a/0x65e [<800a2de4>] bprm_execve+0x1d4/0x316 [<800a351a>] do_execveat_common+0x12e/0x138 [<800a3d44>] __riscv_sys_execve+0x38/0x4e Kernel panic - not syncing: Fatal exception in interrupt This is an arcane bug but we should still fix it. Count down from MAX_ARG_PAGES so the loop ends when index reaches stop, stop == 0 included. The iterations performed are unchanged for every other value of stop. Only CONFIG_MMU=n builds are affected, transfer_args_to_stack() is used by binfmt_flat and binfmt_elf_fdpic on nommu only. The loop predates git history. commit 7e7ec6a93434 ("elf_fdpic_transfer_args_to_stack(): make it generic") only moved it from binfmt_elf_fdpic.c into fs/exec.c and narrowed the copy to the used part of the first page. The condition and the decrement are unchanged from 2.6.12-rc2.

Severity

Not scored

CVSS score

Not available

Vulnerability status

Received

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-08-10 13:20:05.870000

Last modified

2026-11-06 17:19:21.343000

View original CVE JSON

{
  "id": "CVE-2026-68187",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-08-10T13:20:05.870",
  "lastModified": "2026-11-06T17:19:21.343",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nexec: fix unsigned loop counter wrap in transfer_args_to_stack()\n\nThe stop value is derived from bprm->p >> PAGE_SHIFT. The index variable\nis an unsigned long. If bprm->p drops below PAGE_SIZE and stop becomes\nzero the loop condition index >= stop is always true.\n\nAfter the index == 0 iteration the decrement wraps to ULONG_MAX and\nbprm->page[ULONG_MAX] reads sizeof(void *) bytes in front of the array.\nThe pointer has wrapped to -1. That garbage pointer is then passed to\nkmap_local_page() and PAGE_SIZE bytes are copied from wherever that\nlands into the stack of the process being created. And the loop doesn't\nterminate either...\n\nGetting there only requires bprm->p < PAGE_SIZE. On !MMU\nbprm_set_stack_limit() and bprm_hit_stack_limit() are empty. So the only\nconstraint on how far bprm->p is pushed down is valid_arg_len(), i.e.\nthat each individual string still fits in what is left.\n\nbprm->p starts at PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *) so a\nsingle argument or environment string of a little over 31 pages leaves\nit in the first page:\n\n  Oops - load access fault [#1]\n  CPU: 0 UID: 0 PID: 1 Comm: victim Not tainted 7.2.0-rc4 #1\n  epc : __memcpy+0xd4/0xf8\n   ra : transfer_args_to_stack+0xaa/0xae\n   s4 : ffffffffffffffff   s2 : 0000000000000000\n   a1 : ffffffdc98000000   a2 : 0000000000001000\n  status: 0000000a00001880 badaddr: ffffffdc98000000 cause: 0000000000000005\n  [<801a5324>] __memcpy+0xd4/0xf8\n  [<800d5f6a>] load_flat_binary+0x43a/0x65e\n  [<800a2de4>] bprm_execve+0x1d4/0x316\n  [<800a351a>] do_execveat_common+0x12e/0x138\n  [<800a3d44>] __riscv_sys_execve+0x38/0x4e\n  Kernel panic - not syncing: Fatal exception in interrupt\n\nThis is an arcane bug but we should still fix it.\n\nCount down from MAX_ARG_PAGES so the loop ends when index reaches stop,\nstop == 0 included. The iterations performed are unchanged for every\nother value of stop.\n\nOnly CONFIG_MMU=n builds are affected, transfer_args_to_stack() is used\nby binfmt_flat and binfmt_elf_fdpic on nommu only.\n\nThe loop predates git history. commit 7e7ec6a93434\n(\"elf_fdpic_transfer_args_to_stack(): make it generic\") only moved it\nfrom binfmt_elf_fdpic.c into fs/exec.c and narrowed the copy to the used\npart of the first page. The condition and the decrement are unchanged\nfrom 2.6.12-rc2."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "fs/exec.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "a9eb5c4949008034909bc34ecfa0843ecc1d0ab3",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "67cf5cdad823afb0530d6d0341fbf4ca07e93a09",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "66e20942890a383eb39b2009a2ceb4c2ebec37ef",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "c62bb00caba66e01fb578d5f0302f247dc64930a",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "dfc2a00742af4cb7251c1a8fbce4fbae3cc0de4e",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "2bc6bf70d41055377f390d06f0f3521deb62fd3b",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "55fa2c7f2b15583d1a2fe1b5abcc24377359339f",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "lessThan": "16cc4f5c1c4b9e45eca7f7deefa5410a292db599",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "fs/exec.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "2.6.12",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "2.6.12",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.10.265",
              "lessThanOrEqual": "5.10.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.15.216",
              "lessThanOrEqual": "5.15.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.183",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.148",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.101",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18.42",
              "lessThanOrEqual": "6.18.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.1.6",
              "lessThanOrEqual": "7.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-11-06T16:44:04.798177Z",
          "id": "CVE-2026-68187",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/16cc4f5c1c4b9e45eca7f7deefa5410a292db599",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/55fa2c7f2b15583d1a2fe1b5abcc24377359339f",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/66e20942890a383eb39b2009a2ceb4c2ebec37ef",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/67cf5cdad823afb0530d6d0341fbf4ca07e93a09",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/a9eb5c4949008034909bc34ecfa0843ecc1d0ab3",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/c62bb00caba66e01fb578d5f0302f247dc64930a",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
      "url": "https://git.kernel.org/stable/c/dfc2a00742af4cb7251c1a8fbce4fbae3cc0de4e",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
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}