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CVE-2026-45837 (GCVE-0-2026-45837)

Vulnerability from cvelistv5 – Published: 2026-05-27 09:24 – Updated: 2026-06-14 17:46
VLAI
Title
bpf: Fix use-after-free in arena_vm_close on fork
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix use-after-free in arena_vm_close on fork arena_vm_open() only bumps vml->mmap_count but never registers the child VMA in arena->vma_list. The vml->vma always points at the parent VMA, so after parent munmap the pointer dangles. If the child then calls bpf_arena_free_pages(), zap_pages() reads the stale vml->vma triggering use-after-free. Fix this by preventing the arena VMA from being inherited across fork with VM_DONTCOPY, and preventing VMA splits via the may_split callback. Also reject mremap with a .mremap callback returning -EINVAL. A same-size mremap(MREMAP_FIXED) on the full arena VMA reaches copy_vma() through the following path: check_prep_vma() - returns 0 early: new_len == old_len skips VM_DONTEXPAND check prep_move_vma() - vm_start == old_addr and vm_end == old_addr + old_len so may_split is never called move_vma() copy_vma_and_data() copy_vma() vm_area_dup() - copies vm_private_data (vml pointer) vm_ops->open() - bumps vml->mmap_count vm_ops->mremap() - returns -EINVAL, rollback unmaps new VMA The refcount ensures the rollback's arena_vm_close does not free the vml shared with the original VMA.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 317460317a02a1af512697e6e964298dedd8a163 , < 723b9fa930cc277c15ce6b9ec9feec828cfac9d7 (git)
Affected: 317460317a02a1af512697e6e964298dedd8a163 , < d18099f19e53250f8ad2801498b88cec29d9107a (git)
Affected: 317460317a02a1af512697e6e964298dedd8a163 , < 201128fcc7b213d27ab77bc4e89488b41796480f (git)
Affected: 317460317a02a1af512697e6e964298dedd8a163 , < 4fddde2a732de60bb97e3307d4eb69ac5f1d2b74 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.9
Unaffected: 0 , < 6.9 (semver)
Unaffected: 6.12.88 , ≤ 6.12.* (semver)
Unaffected: 6.18.30 , ≤ 6.18.* (semver)
Unaffected: 7.0.7 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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{
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    "dateReserved": "2026-05-13T15:03:33.077Z",
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      "product_status:known_affected": "184",
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      "status": "final",
      "title": "kernel: bpf: Fix use-after-free in arena_vm_close on fork",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-45837.json",
      "version": "3"
    },
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      "current_release_date": "2026-08-31T17:00:50Z",
      "cve": "CVE-2026-45837",
      "id": "CVE-2026-45837",
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      "title": "SUSE CVE CVE-2026-45837",
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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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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.
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  • 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.


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