CVE-2026-45837

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.

CVSS v3 7.8 HIGH

7.8^/10

CVSS v3 : HIGH

Vector :

Exploitability : 1.8 / Impact : 5.9

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://git.kernel.org/stable/c/201128fcc7b213d27ab77bc4e89488b41796480f	Patch
https://git.kernel.org/stable/c/4fddde2a732de60bb97e3307d4eb69ac5f1d2b74	Patch
https://git.kernel.org/stable/c/723b9fa930cc277c15ce6b9ec9feec828cfac9d7	Patch
https://git.kernel.org/stable/c/d18099f19e53250f8ad2801498b88cec29d9107a	Patch

Configurations

Configuration 1 (hide)

OR	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::

History

No history.

Information

Published : 2026-05-27 11:16

Updated : 2026-06-26 19:09

NVD link : CVE-2026-45837

Mitre link : CVE-2026-45837

CVE.ORG link : CVE-2026-45837

JSON object : View

Products Affected

linux

linux_kernel

CWE

CWE-416

Use After Free

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The vml->vma 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->vma 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->open() - bumps vml->mmap_count\n vm_ops->mremap() - 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."}], "lastModified": "2026-06-26T19:09:14.590", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "4CCB4364-CBF5-40DD-AB08-D4665BBE06FB", "versionEndExcluding": "6.12.88", "versionStartIncluding": "6.9"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "BF39AE08-AE6D-4410-8FBE-76F6BF5BF55B", "versionEndExcluding": "6.18.30", "versionStartIncluding": "6.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "D0893CA7-9AE6-4DFE-AC75-48967D73AD8E", "versionEndExcluding": "7.0.7", "versionStartIncluding": "6.19"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}