CVE-2026-80893
In the Linux kernel, the following vulnerability has been resolved:
mm/hugetlb: fix swap entry corruption when clearing uffd-wp at fork()
copy_hugetlb_page_range() clears the uffd-wp bit of migration and hwpoison entries with huge_pte_clear_uffd_wp(), which operates on the present-PTE bit position. Swap entries keep the uffd-wp state elsewhere -- the migration branch reads and sets it with pte_swp_uffd_wp() and pte_swp_mkuffd_wp() -- and the present-PTE position falls into the swap payload. On x86-64 it lands in the inverted swap offset, where a naturally-aligned hugetlb PFN always has the affected bit set, so the clear advances the encoded PFN by two pages.
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No userfaultfd needs to be involved: the clear is guarded only by the child VMA not being uffd-wp registered, so a plain fork() with an in-flight hugetlb migration entry (or a poisoned hugetlb page) corrupts the entry copied into the child. Instrumenting the clear and forking after MADV_HWPOISON on a 2MB anon hugetlb page shows:
The fallout is mostly latent: rmap walks match migration entries by folio range and remove_migration_pte() rebuilds the PTE from the folio, so a within-folio PFN skew heals once migration completes. But any path that re-encodes the corrupted offset -- e.g. hugetlb_change_protection() rewriting a writable migration entry via make_readable_migration_entry(swp_offset(entry)) -- propagates it.
Migration entries legitimately carry uffd-wp, so clear it with pte_swp_clear_uffd_wp(), matching copy_nonpresent_pte() and move_huge_pte().
A hwpoison entry, on the other hand, never carries the uffd-wp bit: it is installed fresh by make_hwpoison_entry() (try_to_unmap_one() does not preserve uffd-wp on the hwpoison path) and hugetlb_change_protection() leaves hwpoison entries untouched. There was nothing to clear there, only the corruption, so drop the clear entirely.
Detalles técnicos trazas, registros y código del informe original
offset before=120e00 offset after =120e02
CVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.21%
- Percentil entre todas las CVEs puntuadas: 11
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
- https://git.kernel.org/stable/c/2b9a07002c2f296aa6a9c591213933d3492e3089
- https://git.kernel.org/stable/c/2fa11c60c9c06bafc19cf4d9efdaa36a38079e87
- https://git.kernel.org/stable/c/69cb5825d9988c7944bc9f1dc08cb233655405a7
- https://git.kernel.org/stable/c/83abe2fd5b3aeb3123b5408a5a91709c5538fb23
- https://git.kernel.org/stable/c/8b0de7005b148738d79d6c45594d566489948a68
- https://git.kernel.org/stable/c/f1b1311c0352873137768bac5a126e491271a747
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-80893",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90",
"lessThan": "f1b1311c0352873137768bac5a126e491271a747",
"versionType": "git"
},
{
"status": "affected",
"version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90",
"lessThan": "69cb5825d9988c7944bc9f1dc08cb233655405a7",
"versionType": "git"
},
{
"status": "affected",
"version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90",
"lessThan": "8b0de7005b148738d79d6c45594d566489948a68",
"versionType": "git"
},
{
"status": "affected",
"version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90",
"lessThan": "2b9a07002c2f296aa6a9c591213933d3492e3089",
"versionType": "git"
},
{
"status": "affected",
"version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90",
"lessThan": "2fa11c60c9c06bafc19cf4d9efdaa36a38079e87",
"versionType": "git"
},
{
"status": "affected",
"version": "bc70fbf269fdff410b0b6d75c3770b9f59117b90",
"lessThan": "83abe2fd5b3aeb3123b5408a5a91709c5538fb23",
"versionType": "git"
}
],
"programFiles": [
"mm/hugetlb.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.19"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.19",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.151",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.103",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.44",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.8",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"mm/hugetlb.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-09-04T18:17:57.467",
"references": [
{
"url": "https://git.kernel.org/stable/c/2b9a07002c2f296aa6a9c591213933d3492e3089",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/2fa11c60c9c06bafc19cf4d9efdaa36a38079e87",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/69cb5825d9988c7944bc9f1dc08cb233655405a7",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/83abe2fd5b3aeb3123b5408a5a91709c5538fb23",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/8b0de7005b148738d79d6c45594d566489948a68",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/f1b1311c0352873137768bac5a126e491271a747",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/hugetlb: fix swap entry corruption when clearing uffd-wp at fork()\n\ncopy_hugetlb_page_range() clears the uffd-wp bit of migration and hwpoison\nentries with huge_pte_clear_uffd_wp(), which operates on the present-PTE\nbit position. Swap entries keep the uffd-wp state elsewhere -- the\nmigration branch reads and sets it with pte_swp_uffd_wp() and\npte_swp_mkuffd_wp() -- and the present-PTE position falls into the swap\npayload. On x86-64 it lands in the inverted swap offset, where a\nnaturally-aligned hugetlb PFN always has the affected bit set, so the\nclear advances the encoded PFN by two pages.\n\nNo userfaultfd needs to be involved: the clear is guarded only by the\nchild VMA not being uffd-wp registered, so a plain fork() with an\nin-flight hugetlb migration entry (or a poisoned hugetlb page) corrupts\nthe entry copied into the child. Instrumenting the clear and forking\nafter MADV_HWPOISON on a 2MB anon hugetlb page shows:\n\n offset before=120e00\n offset after =120e02\n\nThe fallout is mostly latent: rmap walks match migration entries by folio\nrange and remove_migration_pte() rebuilds the PTE from the folio, so a\nwithin-folio PFN skew heals once migration completes. But any path that\nre-encodes the corrupted offset -- e.g. hugetlb_change_protection()\nrewriting a writable migration entry via\nmake_readable_migration_entry(swp_offset(entry)) -- propagates it.\n\nMigration entries legitimately carry uffd-wp, so clear it with\npte_swp_clear_uffd_wp(), matching copy_nonpresent_pte() and\nmove_huge_pte().\n\nA hwpoison entry, on the other hand, never carries the uffd-wp bit: it is\ninstalled fresh by make_hwpoison_entry() (try_to_unmap_one() does not\npreserve uffd-wp on the hwpoison path) and hugetlb_change_protection()\nleaves hwpoison entries untouched. There was nothing to clear there, only\nthe corruption, so drop the clear entirely."
}
],
"lastModified": "2026-09-04T18:17:57.467",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}