CVE-2026-93137 (GCVE-0-2026-93137)
Vulnerability from cvelistv5
Published
2026-09-17 16:11
Modified
2026-10-19 09:06
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: bpf: Fix use-after-free on mm_struct in bpf_find_vma() bpf_find_vma() reads task->mm and calls mmap_read_trylock(mm) without holding a reference on the mm. On a foreign task, a concurrent exit_mm() can free the mm_struct between the lockless read and the trylock, resulting in a use-after-free. mm_struct is not SLAB_TYPESAFE_BY_RCU. For the current task, task->mm is stable. For a foreign task, pin the mm under task->alloc_lock and release it with mmput_async(), mirroring commit d8e27d2d22b6 ("bpf: fix mm lifecycle in open-coded task_vma iterator"). Use spin_trylock() instead of get_task_mm() so BPF context does not block on alloc_lock. Reject irqs-disabled contexts and !CONFIG_MMU on the foreign-task path because dropping the mm reference is not safe there. Race: CPU0 (BPF program) CPU1 (exiting task) ============================ ========================== bpf_find_vma(foreign_task): mm = task->mm exit_mm(): task->mm = NULL mmput(mm) -> frees mm_struct mmap_read_trylock(mm) // UAF on mm
References
Impacted products
Vendor Product Version
Linux Linux Version: 7c7e3d31e7856a8260a254f8c71db416f7f9f5a1
Version: 7c7e3d31e7856a8260a254f8c71db416f7f9f5a1
Version: 7c7e3d31e7856a8260a254f8c71db416f7f9f5a1
Version: 7c7e3d31e7856a8260a254f8c71db416f7f9f5a1
Version: 7c7e3d31e7856a8260a254f8c71db416f7f9f5a1
Version: 7c7e3d31e7856a8260a254f8c71db416f7f9f5a1
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/task_iter.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/task_iter.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.17"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.110",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.188",
                  "versionStartIncluding": "5.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.157",
                  "versionStartIncluding": "5.17",
                  "vulnerable": true
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                {
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix use-after-free on mm_struct in bpf_find_vma()\n\nbpf_find_vma() reads task-\u003emm and calls mmap_read_trylock(mm) without\nholding a reference on the mm. On a foreign task, a concurrent exit_mm()\ncan free the mm_struct between the lockless read and the trylock,\nresulting in a use-after-free. mm_struct is not SLAB_TYPESAFE_BY_RCU.\n\nFor the current task, task-\u003emm is stable. For a foreign task, pin the mm\nunder task-\u003ealloc_lock and release it with mmput_async(), mirroring commit\nd8e27d2d22b6 (\"bpf: fix mm lifecycle in open-coded task_vma iterator\").\nUse spin_trylock() instead of get_task_mm() so BPF context does not block\non alloc_lock. Reject irqs-disabled contexts and !CONFIG_MMU on the\nforeign-task path because dropping the mm reference is not safe there.\n\nRace:\n\n  CPU0 (BPF program)                  CPU1 (exiting task)\n  ============================        ==========================\n  bpf_find_vma(foreign_task):\n    mm = task-\u003emm\n                                      exit_mm():\n                                        task-\u003emm = NULL\n                                        mmput(mm) -\u003e frees mm_struct\n    mmap_read_trylock(mm)\n        // UAF on mm"
        }
      ],
      "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 - bpf_find_vma() is invoked only from a program loaded via bpf(BPF_PROG_LOAD): BPF_PROG_TYPE_SYSCALL (syscall_prog_func_proto) or tracing/raw_tp (bpf_tracing_func_proto), both reaching bpf_base_func_proto() for BPF_FUNC_find_vma. The stale mm comes from bpf_task_from_pid() or a tracing task argument, not from a remote protocol field.\nAC:L - The race is inside bpf_find_vma() between the lockless task-\u003emm load and mmap_read_trylock(mm). The attacker forks a child, looks it up with bpf_task_from_pid(), and hammers BPF_PROG_RUN (or an attached raw_tp) while that child exits so exit_mm()\u2192mmput() frees the mm; they control both sides.\nPR:L - bpf_base_func_proto() returns bpf_find_vma_proto only after bpf_token_capable(CAP_PERFMON); bpf_prog_load() also needs CAP_BPF, and RAW_TRACEPOINT/TRACING fail is_perfmon_prog_type() without CAP_PERFMON. bpf_token_capable() uses ns_capable() on a delegated token\u0027s userns, so this is not init-namespace root.\nUI:N - The attacker loads the program with BPF_PROG_LOAD, runs it via BPF_PROG_RUN or their own attached probe, and exits their own child so exit_mm() races bpf_find_vma(); no other user must mount a filesystem or open a file.\nS:U - mmap_read_trylock() and find_vma() operate on the host kernel mm_struct that bpf_find_vma() cached from task-\u003emm. That is in-kernel memory corruption in the same authority as the bpf() caller, not a KVM/Xen guest-to-host or IOMMU escape.\nC:H - After exit_mm() mmput() frees the mm_struct (mm_cachep is not SLAB_TYPESAFE_BY_RCU), bpf_find_vma() still calls find_vma(mm, start) and hands the resulting vm_area_struct to the BPF callback, so the program can read reallocated kernel VMA/mm memory.\nI:H - The stale mm is used by mmap_read_trylock() (down_read_trylock on mm-\u003emmap_lock) and bpf_mmap_unlock_mm(); those write a freed mm_struct, and find_vma() may walk a reallocated maple tree, which is UAF corruption exploitable for an arbitrary kernel write.\nA:H - down_read_trylock on a freed mm-\u003emmap_lock or find_vma() walking a freed mm-\u003emm_mt oopses or panics the kernel, and the attacker can repeat bpf_find_vma() against children they exit."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:06:10.069Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/db347840d6b6ee9bb9b8e4a985d4b4419f9f3200"
        },
        {
          "url": "https://git.kernel.org/stable/c/8e1101fc4118019a69c96ced4aec93164f89cbd5"
        },
        {
          "url": "https://git.kernel.org/stable/c/c7ad910e987008e125eeff448892e86852173384"
        },
        {
          "url": "https://git.kernel.org/stable/c/86d54cf069fc5ae2e111c87933bebf6eb527978e"
        },
        {
          "url": "https://git.kernel.org/stable/c/2b2a903bee56d312539046d9defa8023eec94760"
        },
        {
          "url": "https://git.kernel.org/stable/c/47b079e2117a2ee52e21f8b72935900c702fc0b5"
        }
      ],
      "title": "bpf: Fix use-after-free on mm_struct in bpf_find_vma()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-93137",
    "datePublished": "2026-09-17T16:11:38.135Z",
    "dateReserved": "2026-09-17T16:02:15.088Z",
    "dateUpdated": "2026-10-19T09:06:10.069Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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