FKIE_CVE-2025-40271
Vulnerability from fkie_nvd - Published: 2025-12-06 22:15 - Updated: 2026-07-30 06:24
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
fs/proc: fix uaf in proc_readdir_de()
Pde is erased from subdir rbtree through rb_erase(), but not set the node
to EMPTY, which may result in uaf access. We should use RB_CLEAR_NODE()
set the erased node to EMPTY, then pde_subdir_next() will return NULL to
avoid uaf access.
We found an uaf issue while using stress-ng testing, need to run testcase
getdent and tun in the same time. The steps of the issue is as follows:
1) use getdent to traverse dir /proc/pid/net/dev_snmp6/, and current
pde is tun3;
2) in the [time windows] unregister netdevice tun3 and tun2, and erase
them from rbtree. erase tun3 first, and then erase tun2. the
pde(tun2) will be released to slab;
3) continue to getdent process, then pde_subdir_next() will return
pde(tun2) which is released, it will case uaf access.
CPU 0 | CPU 1
-------------------------------------------------------------------------
traverse dir /proc/pid/net/dev_snmp6/ | unregister_netdevice(tun->dev) //tun3 tun2
sys_getdents64() |
iterate_dir() |
proc_readdir() |
proc_readdir_de() | snmp6_unregister_dev()
pde_get(de); | proc_remove()
read_unlock(&proc_subdir_lock); | remove_proc_subtree()
| write_lock(&proc_subdir_lock);
[time window] | rb_erase(&root->subdir_node, &parent->subdir);
| write_unlock(&proc_subdir_lock);
read_lock(&proc_subdir_lock); |
next = pde_subdir_next(de); |
pde_put(de); |
de = next; //UAF |
rbtree of dev_snmp6
|
pde(tun3)
/ \
NULL pde(tun2)
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/proc/generic.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "1d1596d68a6f11d28f677eedf6cf5b17dbfeb491",
"status": "affected",
"version": "710585d4922fd315f2cada8fbe550ae8ed23e994",
"versionType": "git"
},
{
"lessThan": "c81d0385500446efe48c305bbb83d47f2ae23a50",
"status": "affected",
"version": "710585d4922fd315f2cada8fbe550ae8ed23e994",
"versionType": "git"
},
{
"lessThan": "4cba73c4c89219beef7685a47374bf88b1022369",
"status": "affected",
"version": "710585d4922fd315f2cada8fbe550ae8ed23e994",
"versionType": "git"
},
{
"lessThan": "6f2482745e510ae1dacc9b090194b9c5f918d774",
"status": "affected",
"version": "710585d4922fd315f2cada8fbe550ae8ed23e994",
"versionType": "git"
},
{
"lessThan": "67272c11f379d9aa5e0f6b16286b9d89b3f76046",
"status": "affected",
"version": "710585d4922fd315f2cada8fbe550ae8ed23e994",
"versionType": "git"
},
{
"lessThan": "623bb26127fb581a741e880e1e1a47d79aecb6f8",
"status": "affected",
"version": "710585d4922fd315f2cada8fbe550ae8ed23e994",
"versionType": "git"
},
{
"lessThan": "03de7ff197a3d0e17d0d5c58fdac99a63cba8110",
"status": "affected",
"version": "710585d4922fd315f2cada8fbe550ae8ed23e994",
"versionType": "git"
},
{
"lessThan": "895b4c0c79b092d732544011c3cecaf7322c36a1",
"status": "affected",
"version": "710585d4922fd315f2cada8fbe550ae8ed23e994",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/proc/generic.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "3.19"
},
{
"lessThan": "3.19",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.4.*",
"status": "unaffected",
"version": "5.4.302",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.247",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.197",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.159",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.117",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.59",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.17.*",
"status": "unaffected",
"version": "6.17.9",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.18",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"affectedData": [
{
"defaultStatus": "unknown",
"product": "RUGGEDCOM RST2428P",
"vendor": "Siemens",
"versions": [
{
"lessThan": "V4.0",
"status": "affected",
"version": "0",
"versionType": "custom"
}
]
}
],
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/proc: fix uaf in proc_readdir_de()\n\nPde is erased from subdir rbtree through rb_erase(), but not set the node\nto EMPTY, which may result in uaf access. We should use RB_CLEAR_NODE()\nset the erased node to EMPTY, then pde_subdir_next() will return NULL to\navoid uaf access.\n\nWe found an uaf issue while using stress-ng testing, need to run testcase\ngetdent and tun in the same time. The steps of the issue is as follows:\n\n1) use getdent to traverse dir /proc/pid/net/dev_snmp6/, and current\n pde is tun3;\n\n2) in the [time windows] unregister netdevice tun3 and tun2, and erase\n them from rbtree. erase tun3 first, and then erase tun2. the\n pde(tun2) will be released to slab;\n\n3) continue to getdent process, then pde_subdir_next() will return\n pde(tun2) which is released, it will case uaf access.\n\nCPU 0 | CPU 1\n-------------------------------------------------------------------------\ntraverse dir /proc/pid/net/dev_snmp6/ | unregister_netdevice(tun-\u003edev) //tun3 tun2\nsys_getdents64() |\n iterate_dir() |\n proc_readdir() |\n proc_readdir_de() | snmp6_unregister_dev()\n pde_get(de); | proc_remove()\n read_unlock(\u0026proc_subdir_lock); | remove_proc_subtree()\n | write_lock(\u0026proc_subdir_lock);\n [time window] | rb_erase(\u0026root-\u003esubdir_node, \u0026parent-\u003esubdir);\n | write_unlock(\u0026proc_subdir_lock);\n read_lock(\u0026proc_subdir_lock); |\n next = pde_subdir_next(de); |\n pde_put(de); |\n de = next; //UAF |\n\nrbtree of dev_snmp6\n |\n pde(tun3)\n / \\\n NULL pde(tun2)"
}
],
"id": "CVE-2025-40271",
"lastModified": "2026-07-30T06:24:24.733",
"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"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2025-40271",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-06-16T19:37:49.226666Z",
"version": "2.0.3"
}
}
]
},
"published": "2025-12-06T22:15:54.737",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/03de7ff197a3d0e17d0d5c58fdac99a63cba8110"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/1d1596d68a6f11d28f677eedf6cf5b17dbfeb491"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/4cba73c4c89219beef7685a47374bf88b1022369"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/623bb26127fb581a741e880e1e1a47d79aecb6f8"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/67272c11f379d9aa5e0f6b16286b9d89b3f76046"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/6f2482745e510ae1dacc9b090194b9c5f918d774"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/895b4c0c79b092d732544011c3cecaf7322c36a1"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/c81d0385500446efe48c305bbb83d47f2ae23a50"
},
{
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-253495.html"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Deferred"
}
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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.
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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.
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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.
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