FKIE_CVE-2026-45837
Vulnerability from fkie_nvd - Published: 2026-05-27 11:16 - Updated: 2026-06-26 19:09
Severity
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.
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * |
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"kernel/bpf/arena.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "723b9fa930cc277c15ce6b9ec9feec828cfac9d7",
"status": "affected",
"version": "317460317a02a1af512697e6e964298dedd8a163",
"versionType": "git"
},
{
"lessThan": "d18099f19e53250f8ad2801498b88cec29d9107a",
"status": "affected",
"version": "317460317a02a1af512697e6e964298dedd8a163",
"versionType": "git"
},
{
"lessThan": "201128fcc7b213d27ab77bc4e89488b41796480f",
"status": "affected",
"version": "317460317a02a1af512697e6e964298dedd8a163",
"versionType": "git"
},
{
"lessThan": "4fddde2a732de60bb97e3307d4eb69ac5f1d2b74",
"status": "affected",
"version": "317460317a02a1af512697e6e964298dedd8a163",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"kernel/bpf/arena.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.9"
},
{
"lessThan": "6.9",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.88",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.30",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.0.*",
"status": "unaffected",
"version": "7.0.7",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "4CCB4364-CBF5-40DD-AB08-D4665BBE06FB",
"versionEndExcluding": "6.12.88",
"versionStartIncluding": "6.9",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "BF39AE08-AE6D-4410-8FBE-76F6BF5BF55B",
"versionEndExcluding": "6.18.30",
"versionStartIncluding": "6.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "D0893CA7-9AE6-4DFE-AC75-48967D73AD8E",
"versionEndExcluding": "7.0.7",
"versionStartIncluding": "6.19",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "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\u0027s arena_vm_close does not free\nthe vml shared with the original VMA."
}
],
"id": "CVE-2026-45837",
"lastModified": "2026-06-26T19:09:14.590",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "nvd@nist.gov",
"type": "Primary"
}
]
},
"published": "2026-05-27T11:16:23.020",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/201128fcc7b213d27ab77bc4e89488b41796480f"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/4fddde2a732de60bb97e3307d4eb69ac5f1d2b74"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/723b9fa930cc277c15ce6b9ec9feec828cfac9d7"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/d18099f19e53250f8ad2801498b88cec29d9107a"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-416"
}
],
"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
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Browse all ATT&CK techniques and the vulnerabilities related to each.
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