CVE-2021-47461 (GCVE-0-2021-47461)
Vulnerability from cvelistv5 – Published: 2024-05-22 06:23 – Updated: 2026-08-05 08:47
VLAI
EPSS
VEX
Title
userfaultfd: fix a race between writeprotect and exit_mmap()
Summary
In the Linux kernel, the following vulnerability has been resolved:
userfaultfd: fix a race between writeprotect and exit_mmap()
A race is possible when a process exits, its VMAs are removed by
exit_mmap() and at the same time userfaultfd_writeprotect() is called.
The race was detected by KASAN on a development kernel, but it appears
to be possible on vanilla kernels as well.
Use mmget_not_zero() to prevent the race as done in other userfaultfd
operations.
Severity
7.8 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-05-22 18:15 UTC
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 , < 3cda4bfffd4f755645577aaa9e96a606657b4525
(git)
Affected: 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 , < 149958ecd0627a9f1e9c678c25c665400054cd6a (git) Affected: 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 , < cb185d5f1ebf900f4ae3bf84cee212e6dd035aca (git) |
guessed | |
| Linux | Linux |
Affected:
5.7
Unaffected: 0 , < 5.7 (semver) Unaffected: 5.10.76 , ≤ 5.10.* (semver) Unaffected: 5.14.15 , ≤ 5.14.* (semver) Unaffected: 5.15 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2021-47461",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2024-05-22T18:15:05.306200Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2024-06-04T17:15:25.867Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
},
{
"providerMetadata": {
"dateUpdated": "2024-08-04T05:39:59.468Z",
"orgId": "af854a3a-2127-422b-91ae-364da2661108",
"shortName": "CVE"
},
"references": [
{
"tags": [
"x_transferred"
],
"url": "https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525"
},
{
"tags": [
"x_transferred"
],
"url": "https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a"
},
{
"tags": [
"x_transferred"
],
"url": "https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca"
}
],
"title": "CVE Program Container"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/userfaultfd.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "3cda4bfffd4f755645577aaa9e96a606657b4525",
"status": "affected",
"version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
"versionType": "git"
},
{
"lessThan": "149958ecd0627a9f1e9c678c25c665400054cd6a",
"status": "affected",
"version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
"versionType": "git"
},
{
"lessThan": "cb185d5f1ebf900f4ae3bf84cee212e6dd035aca",
"status": "affected",
"version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/userfaultfd.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.7"
},
{
"lessThan": "5.7",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.76",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.14.*",
"status": "unaffected",
"version": "5.14.15",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "5.15",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.10.76",
"versionStartIncluding": "5.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.14.15",
"versionStartIncluding": "5.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15",
"versionStartIncluding": "5.7",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nuserfaultfd: fix a race between writeprotect and exit_mmap()\n\nA race is possible when a process exits, its VMAs are removed by\nexit_mmap() and at the same time userfaultfd_writeprotect() is called.\n\nThe race was detected by KASAN on a development kernel, but it appears\nto be possible on vanilla kernels as well.\n\nUse mmget_not_zero() to prevent the race as done in other userfaultfd\noperations."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The bug is reached only via the local userfaultfd(2) syscall and UFFDIO_WRITEPROTECT ioctl into userfaultfd_writeprotect()/mwriteprotect_range(), not via network packet processing or physical device I/O.\nAC:L - The attacker fully controls both sides of the race by creating a userfaultfd, registering a WP range, sharing the fd (fork/SCM_RIGHTS), exiting the mm owner so exit_mmap() frees VMAs, and concurrently issuing UFFDIO_WRITEPROTECT from the fd holder.\nPR:L - Any unprivileged user can open userfaultfd with UFFD_USER_MODE_ONLY (allowed by default) and use UFFDIO_WRITEPROTECT; CAP_SYS_PTRACE is not required for this path.\nUI:N - The attacker performs the uffd setup, fd sharing, process exit, and ioctl hammering themselves; no separate victim action is required.\nS:U - This is a standard in-kernel VMA use-after-free within the host kernel authority, with no VM escape, IOMMU bypass, or other cross-boundary impact.\nC:H - The race is a use-after-free on VMA structures (KASAN-detected) while find_vma/change_protection still touch them; UAF enables reclaim/spray and arbitrary kernel memory disclosure.\nI:H - Use-after-free of VMAs during change_protection allows heap manipulation of VMA state that drives page-table writes, enabling arbitrary write and control-flow hijacking primitives.\nA:H - Concurrent exit_mmap() freeing of VMAs while mwriteprotect_range() walks and modifies them causes kernel oops/panic even when not fully exploited for code execution."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-05T08:47:57.329Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525"
},
{
"url": "https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a"
},
{
"url": "https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca"
}
],
"title": "userfaultfd: fix a race between writeprotect and exit_mmap()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2021-47461",
"datePublished": "2024-05-22T06:23:22.373Z",
"dateReserved": "2024-05-22T06:20:56.197Z",
"dateUpdated": "2026-08-05T08:47:57.329Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2021-47461",
"date": "2026-09-19",
"epss": "0.00173",
"percentile": "0.07044"
},
"fkie_nvd": {
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nuserfaultfd: fix a race between writeprotect and exit_mmap()\n\nA race is possible when a process exits, its VMAs are removed by\nexit_mmap() and at the same time userfaultfd_writeprotect() is called.\n\nThe race was detected by KASAN on a development kernel, but it appears\nto be possible on vanilla kernels as well.\n\nUse mmget_not_zero() to prevent the race as done in other userfaultfd\noperations."
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: userfaultfd: corrige una ejecuci\u00f3n entre writeprotect y exit_mmap() Una ejecuci\u00f3n es posible cuando un proceso sale, sus VMA son eliminados por exit_mmap() y al mismo tiempo se llama a userfaultfd_writeprotect() . KASAN detect\u00f3 la ejecuci\u00f3n en un n\u00facleo de desarrollo, pero parece ser posible tambi\u00e9n en n\u00facleos de vainilla. Utilice mmget_not_zero() para evitar la ejecuci\u00f3n como se hace en otras operaciones de userfaultfd."
}
],
"id": "CVE-2021-47461",
"lastModified": "2024-11-21T06:36:12.090",
"published": "2024-05-22T07:15:11.040",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca"
},
{
"source": "af854a3a-2127-422b-91ae-364da2661108",
"url": "https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a"
},
{
"source": "af854a3a-2127-422b-91ae-364da2661108",
"url": "https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525"
},
{
"source": "af854a3a-2127-422b-91ae-364da2661108",
"url": "https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/userfaultfd.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "3cda4bfffd4f755645577aaa9e96a606657b4525",
"status": "affected",
"version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
"versionType": "git"
},
{
"lessThan": "149958ecd0627a9f1e9c678c25c665400054cd6a",
"status": "affected",
"version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
"versionType": "git"
},
{
"lessThan": "cb185d5f1ebf900f4ae3bf84cee212e6dd035aca",
"status": "affected",
"version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/userfaultfd.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.7"
},
{
"lessThan": "5.7",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.76",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.14.*",
"status": "unaffected",
"version": "5.14.15",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "5.15",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "337EB464-BC23-4BF5-B901-A933B3ABA6A7",
"versionEndExcluding": "5.10.76",
"versionStartIncluding": "5.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "63BD46C4-473F-45F9-93E9-F67D955321D8",
"versionEndExcluding": "5.14.15",
"versionStartIncluding": "5.11",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:*",
"matchCriteriaId": "E46C74C6-B76B-4C94-A6A4-FD2FFF62D644",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:*",
"matchCriteriaId": "60134C3A-06E4-48C1-B04F-2903732A4E56",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:*",
"matchCriteriaId": "0460DA88-8FE1-46A2-9DDA-1F1ABA552E71",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc4:*:*:*:*:*:*",
"matchCriteriaId": "AF55383D-4DF2-45DC-93F7-571F4F978EAB",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc5:*:*:*:*:*:*",
"matchCriteriaId": "9E9481B2-8AA6-4CBD-B5D3-C10F51FF6D01",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:5.15:rc6:*:*:*:*:*:*",
"matchCriteriaId": "EBD45831-4B79-42BC-ABC0-86870F0DEA89",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nuserfaultfd: fix a race between writeprotect and exit_mmap()\n\nA race is possible when a process exits, its VMAs are removed by\nexit_mmap() and at the same time userfaultfd_writeprotect() is called.\n\nThe race was detected by KASAN on a development kernel, but it appears\nto be possible on vanilla kernels as well.\n\nUse mmget_not_zero() to prevent the race as done in other userfaultfd\noperations."
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: userfaultfd: corrige una ejecuci\u00f3n entre writeprotect y exit_mmap() Una ejecuci\u00f3n es posible cuando un proceso sale, sus VMA son eliminados por exit_mmap() y al mismo tiempo se llama a userfaultfd_writeprotect() . KASAN detect\u00f3 la ejecuci\u00f3n en un n\u00facleo de desarrollo, pero parece ser posible tambi\u00e9n en n\u00facleos de vainilla. Utilice mmget_not_zero() para evitar la ejecuci\u00f3n como se hace en otras operaciones de userfaultfd."
}
],
"id": "CVE-2021-47461",
"lastModified": "2026-08-04T10:17:04.587",
"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": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
},
{
"cvssData": {
"attackComplexity": "HIGH",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 4.7,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.0,
"impactScore": 3.6,
"source": "nvd@nist.gov",
"type": "Primary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2021-47461",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2024-05-22T18:15:05.306200Z",
"version": "2.0.3"
}
}
]
},
"published": "2024-05-22T07:15:11.040",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca"
},
{
"source": "af854a3a-2127-422b-91ae-364da2661108",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a"
},
{
"source": "af854a3a-2127-422b-91ae-364da2661108",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525"
},
{
"source": "af854a3a-2127-422b-91ae-364da2661108",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Modified",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-362"
}
],
"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-08-04T19:57:19+00:00",
"cve": "CVE-2021-47461",
"id": "CVE-2021-47461",
"initial_release_date": "2021-01-01T00:00:00+00:00",
"product_status:fixed": "413",
"product_status:known_affected": "42",
"product_status:known_not_affected": "111",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: userfaultfd: fix a race between writeprotect and exit_mmap()",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-47461.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-08-14T01:32:33Z",
"cve": "CVE-2021-47461",
"id": "CVE-2021-47461",
"initial_release_date": "2024-05-25T03:33:56Z",
"product_status:known_affected": "275",
"product_status:known_not_affected": "217",
"product_status:recommended": "472",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2021-47461",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2021-47461.json",
"version": "53"
},
"vulnrichment": {
"containers": {
"adp": [
{
"providerMetadata": {
"dateUpdated": "2024-08-04T05:39:59.468Z",
"orgId": "af854a3a-2127-422b-91ae-364da2661108",
"shortName": "CVE"
},
"references": [
{
"tags": [
"x_transferred"
],
"url": "https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525"
},
{
"tags": [
"x_transferred"
],
"url": "https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a"
},
{
"tags": [
"x_transferred"
],
"url": "https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca"
}
],
"title": "CVE Program Container"
},
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2021-47461",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2024-05-22T18:15:05.306200Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2024-05-23T19:01:25.597Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/userfaultfd.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "3cda4bfffd4f755645577aaa9e96a606657b4525",
"status": "affected",
"version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
"versionType": "git"
},
{
"lessThan": "149958ecd0627a9f1e9c678c25c665400054cd6a",
"status": "affected",
"version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
"versionType": "git"
},
{
"lessThan": "cb185d5f1ebf900f4ae3bf84cee212e6dd035aca",
"status": "affected",
"version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/userfaultfd.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.7"
},
{
"lessThan": "5.7",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.76",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.14.*",
"status": "unaffected",
"version": "5.14.15",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "5.15",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.10.76",
"versionStartIncluding": "5.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.14.15",
"versionStartIncluding": "5.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15",
"versionStartIncluding": "5.7",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nuserfaultfd: fix a race between writeprotect and exit_mmap()\n\nA race is possible when a process exits, its VMAs are removed by\nexit_mmap() and at the same time userfaultfd_writeprotect() is called.\n\nThe race was detected by KASAN on a development kernel, but it appears\nto be possible on vanilla kernels as well.\n\nUse mmget_not_zero() to prevent the race as done in other userfaultfd\noperations."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The bug is reached only via the local userfaultfd(2) syscall and UFFDIO_WRITEPROTECT ioctl into userfaultfd_writeprotect()/mwriteprotect_range(), not via network packet processing or physical device I/O.\nAC:L - The attacker fully controls both sides of the race by creating a userfaultfd, registering a WP range, sharing the fd (fork/SCM_RIGHTS), exiting the mm owner so exit_mmap() frees VMAs, and concurrently issuing UFFDIO_WRITEPROTECT from the fd holder.\nPR:L - Any unprivileged user can open userfaultfd with UFFD_USER_MODE_ONLY (allowed by default) and use UFFDIO_WRITEPROTECT; CAP_SYS_PTRACE is not required for this path.\nUI:N - The attacker performs the uffd setup, fd sharing, process exit, and ioctl hammering themselves; no separate victim action is required.\nS:U - This is a standard in-kernel VMA use-after-free within the host kernel authority, with no VM escape, IOMMU bypass, or other cross-boundary impact.\nC:H - The race is a use-after-free on VMA structures (KASAN-detected) while find_vma/change_protection still touch them; UAF enables reclaim/spray and arbitrary kernel memory disclosure.\nI:H - Use-after-free of VMAs during change_protection allows heap manipulation of VMA state that drives page-table writes, enabling arbitrary write and control-flow hijacking primitives.\nA:H - Concurrent exit_mmap() freeing of VMAs while mwriteprotect_range() walks and modifies them causes kernel oops/panic even when not fully exploited for code execution."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-05T08:47:57.329Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/3cda4bfffd4f755645577aaa9e96a606657b4525"
},
{
"url": "https://git.kernel.org/stable/c/149958ecd0627a9f1e9c678c25c665400054cd6a"
},
{
"url": "https://git.kernel.org/stable/c/cb185d5f1ebf900f4ae3bf84cee212e6dd035aca"
}
],
"title": "userfaultfd: fix a race between writeprotect and exit_mmap()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2021-47461",
"datePublished": "2024-05-22T06:23:22.373Z",
"dateReserved": "2024-05-22T06:20:56.197Z",
"dateUpdated": "2026-08-05T08:47:57.329Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
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.
Sightings
| Author | Source | Type | Date | Other |
|---|
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.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- 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.
Loading…
The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Loading…
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
Loading…