CVE-2026-98214
In the Linux kernel, the following vulnerability has been resolved:
selinux: recheck intermediate backing files on mprotect()
mprotect() can be used to bypass the SELinux checks that mmap() performs against the intermediate layers of a stacked filesystem.
mmap() checks every backing layer as the request descends through the stack. mprotect() only has the lowest backing file in vma->vm_file, so it rechecks the top-level user and the lowest mounter, but skips the mounters of every layer in between. With two nested overlayfs mounts and a policy denying mounter_t -> middle_file_t:file { execute }, a direct mmap(PROT_EXEC) is denied:
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while mmap(PROT_NONE) followed by mprotect(PROT_EXEC) succeeds.
Preserve each intermediate path, mounter SID and file-description SID in the backing-file security blob, copying the saved entries when another backing layer is opened. Allocate the array only for nested backing files, and release it and the path references in the backing_file_free hook.
During mprotect(), recheck fd { use } and the requested inode permissions for every saved mounter, and include the intermediate layers in the execmod checks. Policy for nested stacking may then need to grant intermediate mounters what a direct mmap() already requires, and execmod on intermediate labels for binaries using text relocations.
Tested on arm64 QEMU with a small BusyBox initramfs and a purpose-built SELinux policy, on a mainline tree containing commit f2381b546e7e ("fs: fix user path of nested backing files").
[PM: subject tweak]
Detalles técnicos trazas, registros y código del informe original
avc: denied { execute } for pid=71 comm="nested_exec"
path="/payload" dev="overlay" ino=9
scontext=user_u:base_r:mounter_t
tcontext=user_u:object_r:middle_file_t tclass=file permissive=0CVSS
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: 0.22%
- 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/4d50ebe5a27724e020747ffd61a051dec67cb8ec
- https://git.kernel.org/stable/c/78fc54b934bfb2c18aad8154c7302067146946f9
- https://git.kernel.org/stable/c/89376fbfdcc1a728e1775f98752cdd90b0930a00
- https://git.kernel.org/stable/c/c2bbb905af2293549651b614a52ad91e0b462b60
- https://git.kernel.org/stable/c/d127c7e1f3e1231d8ac8b2738e3f00bea12afe74
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-98214",
"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": "bc6c380c1159de52a252ed11f19a42c47f60a735",
"lessThan": "4d50ebe5a27724e020747ffd61a051dec67cb8ec",
"versionType": "git"
},
{
"status": "affected",
"version": "8bacd09f12c27710228562e4d13163e58c5f4a45",
"lessThan": "89376fbfdcc1a728e1775f98752cdd90b0930a00",
"versionType": "git"
},
{
"status": "affected",
"version": "d844702198395d3f80222777030f69db6be6b709",
"lessThan": "d127c7e1f3e1231d8ac8b2738e3f00bea12afe74",
"versionType": "git"
},
{
"status": "affected",
"version": "82544d36b1729153c8aeb179e84750f0c085d3b1",
"lessThan": "c2bbb905af2293549651b614a52ad91e0b462b60",
"versionType": "git"
},
{
"status": "affected",
"version": "82544d36b1729153c8aeb179e84750f0c085d3b1",
"lessThan": "78fc54b934bfb2c18aad8154c7302067146946f9",
"versionType": "git"
},
{
"status": "affected",
"version": "cd0e707a927a70cdfd8bc5a512a9719a87f5ed51",
"versionType": "git"
},
{
"status": "affected",
"version": "6.6.144",
"lessThan": "6.6.158",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.12.95",
"lessThan": "6.12.112",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.18.38",
"lessThan": "6.18.54",
"versionType": "semver"
},
{
"status": "affected",
"version": "7.0.4",
"lessThan": "7.1",
"versionType": "semver"
}
],
"programFiles": [
"security/selinux/hooks.c",
"security/selinux/include/objsec.h"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "7.1"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "7.1",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.158",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.112",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.54",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.8",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3-rc4",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"security/selinux/hooks.c",
"security/selinux/include/objsec.h"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-10-06T09:18:07.943",
"references": [
{
"url": "https://git.kernel.org/stable/c/4d50ebe5a27724e020747ffd61a051dec67cb8ec",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/78fc54b934bfb2c18aad8154c7302067146946f9",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/89376fbfdcc1a728e1775f98752cdd90b0930a00",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/c2bbb905af2293549651b614a52ad91e0b462b60",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/d127c7e1f3e1231d8ac8b2738e3f00bea12afe74",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nselinux: recheck intermediate backing files on mprotect()\n\nmprotect() can be used to bypass the SELinux checks that mmap() performs\nagainst the intermediate layers of a stacked filesystem.\n\nmmap() checks every backing layer as the request descends through the\nstack. mprotect() only has the lowest backing file in vma->vm_file, so it\nrechecks the top-level user and the lowest mounter, but skips the mounters\nof every layer in between. With two nested overlayfs mounts and a policy\ndenying mounter_t -> middle_file_t:file { execute }, a direct\nmmap(PROT_EXEC) is denied:\n\n avc: denied { execute } for pid=71 comm=\"nested_exec\"\n path=\"/payload\" dev=\"overlay\" ino=9\n scontext=user_u:base_r:mounter_t\n tcontext=user_u:object_r:middle_file_t tclass=file permissive=0\n\nwhile mmap(PROT_NONE) followed by mprotect(PROT_EXEC) succeeds.\n\nPreserve each intermediate path, mounter SID and file-description SID in\nthe backing-file security blob, copying the saved entries when another\nbacking layer is opened. Allocate the array only for nested backing files,\nand release it and the path references in the backing_file_free hook.\n\nDuring mprotect(), recheck fd { use } and the requested inode permissions\nfor every saved mounter, and include the intermediate layers in the execmod\nchecks. Policy for nested stacking may then need to grant intermediate\nmounters what a direct mmap() already requires, and execmod on intermediate\nlabels for binaries using text relocations.\n\nTested on arm64 QEMU with a small BusyBox initramfs and a purpose-built\nSELinux policy, on a mainline tree containing\ncommit f2381b546e7e (\"fs: fix user path of nested backing files\").\n\n[PM: subject tweak]"
}
],
"lastModified": "2026-10-06T09:18:07.943",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}