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CVE-2025-40271 (GCVE-0-2025-40271)

Vulnerability from cvelistv5 – Published: 2025-12-06 21:50 – Updated: 2026-08-05 12:09
VLAI
Title
fs/proc: fix uaf in proc_readdir_de()
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)
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-16 19:37 UTC
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 710585d4922fd315f2cada8fbe550ae8ed23e994 , < 1d1596d68a6f11d28f677eedf6cf5b17dbfeb491 (git)
Affected: 710585d4922fd315f2cada8fbe550ae8ed23e994 , < c81d0385500446efe48c305bbb83d47f2ae23a50 (git)
Affected: 710585d4922fd315f2cada8fbe550ae8ed23e994 , < 4cba73c4c89219beef7685a47374bf88b1022369 (git)
Affected: 710585d4922fd315f2cada8fbe550ae8ed23e994 , < 6f2482745e510ae1dacc9b090194b9c5f918d774 (git)
Affected: 710585d4922fd315f2cada8fbe550ae8ed23e994 , < 67272c11f379d9aa5e0f6b16286b9d89b3f76046 (git)
Affected: 710585d4922fd315f2cada8fbe550ae8ed23e994 , < 623bb26127fb581a741e880e1e1a47d79aecb6f8 (git)
Affected: 710585d4922fd315f2cada8fbe550ae8ed23e994 , < 03de7ff197a3d0e17d0d5c58fdac99a63cba8110 (git)
Affected: 710585d4922fd315f2cada8fbe550ae8ed23e994 , < 895b4c0c79b092d732544011c3cecaf7322c36a1 (git)
guessed Create a notification for this product.
Linux Linux Affected: 3.19
Unaffected: 0 , < 3.19 (semver)
Unaffected: 5.4.302 , ≤ 5.4.* (semver)
Unaffected: 5.10.247 , ≤ 5.10.* (semver)
Unaffected: 5.15.197 , ≤ 5.15.* (semver)
Unaffected: 6.1.159 , ≤ 6.1.* (semver)
Unaffected: 6.6.117 , ≤ 6.6.* (semver)
Unaffected: 6.12.59 , ≤ 6.12.* (semver)
Unaffected: 6.17.9 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Siemens RUGGEDCOM RST2428P Affected: 0 , < V4.0 (custom)
guessed Create a notification for this product.
Show details on NVD website
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            "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": {
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                "availabilityImpact": "HIGH",
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                "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",
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        "references": [
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            "url": "https://cert-portal.siemens.com/productcert/html/ssa-253495.html"
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        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Deferred"
      }
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    "redhat_vex": {
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      "current_release_date": "2026-07-30T08:37:53+00:00",
      "cve": "CVE-2025-40271",
      "id": "CVE-2025-40271",
      "initial_release_date": "2025-12-06T00:00:00+00:00",
      "product_status:fixed": "2410",
      "product_status:known_affected": "22",
      "product_status:known_not_affected": "20",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Linux kernel: Use-after-free in proc_readdir_de() can lead to privilege escalation or denial of service.",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40271.json",
      "version": "3"
    },
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      "current_release_date": "2026-08-28T16:54:22Z",
      "cve": "CVE-2025-40271",
      "id": "CVE-2025-40271",
      "initial_release_date": "2025-12-08T00:23:21Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "711",
      "product_status:known_not_affected": "99",
      "product_status:recommended": "442",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-40271",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-40271.json",
      "version": "50"
    },
    "vulnrichment": {
      "containers": {
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          {
            "affected": [
              {
                "defaultStatus": "unknown",
                "product": "RUGGEDCOM RST2428P",
                "vendor": "Siemens",
                "versions": [
                  {
                    "lessThan": "V4.0",
                    "status": "affected",
                    "version": "0",
                    "versionType": "custom"
                  }
                ]
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-06-02T13:00:17.378Z",
              "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
              "shortName": "siemens-SADP"
            },
            "references": [
              {
                "url": "https://cert-portal.siemens.com/productcert/html/ssa-253495.html"
              }
            ],
            "x_adpType": "supplier"
          },
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2025-40271",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-06-16T19:37:49.226666Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
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              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-06-16T19:37:56.227Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "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": [
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                {
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                  "version": "710585d4922fd315f2cada8fbe550ae8ed23e994",
                  "versionType": "git"
                },
                {
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                  "status": "affected",
                  "version": "710585d4922fd315f2cada8fbe550ae8ed23e994",
                  "versionType": "git"
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                {
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                  "status": "affected",
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                  "status": "affected",
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              "product": "Linux",
              "programFiles": [
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
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                  "version": "3.19"
                },
                {
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                  "status": "unaffected",
                  "version": "0",
                  "versionType": "semver"
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                  "status": "unaffected",
                  "version": "5.4.302",
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                  "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"
                },
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                  "status": "unaffected",
                  "version": "6.6.117",
                  "versionType": "semver"
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                  "status": "unaffected",
                  "version": "6.12.59",
                  "versionType": "semver"
                },
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                  "status": "unaffected",
                  "version": "6.17.9",
                  "versionType": "semver"
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                  "status": "unaffected",
                  "version": "6.18",
                  "versionType": "original_commit_for_fix"
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          ],
          "cpeApplicability": [
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              "nodes": [
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                  "cpeMatch": [
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                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                      "versionStartIncluding": "3.19",
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              "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)"
            }
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}



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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.


Detection rules are retrieved from Rulezet.


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.