CVE-2025-21731 (GCVE-0-2025-21731)

Vulnerability from cvelistv5 – Published: 2025-02-27 02:07 – Updated: 2026-10-15 01:03
VLAI
Title
nbd: don't allow reconnect after disconnect
Summary
In the Linux kernel, the following vulnerability has been resolved: nbd: don't allow reconnect after disconnect Following process can cause nbd_config UAF: 1) grab nbd_config temporarily; 2) nbd_genl_disconnect() flush all recv_work() and release the initial reference: nbd_genl_disconnect nbd_disconnect_and_put nbd_disconnect flush_workqueue(nbd->recv_workq) if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF, ...)) nbd_config_put -> due to step 1), reference is still not zero 3) nbd_genl_reconfigure() queue recv_work() again; nbd_genl_reconfigure config = nbd_get_config_unlocked(nbd) if (!config) -> succeed if (!test_bit(NBD_RT_BOUND, ...)) -> succeed nbd_reconnect_socket queue_work(nbd->recv_workq, &args->work) 4) step 1) release the reference; 5) Finially, recv_work() will trigger UAF: recv_work nbd_config_put(nbd) -> nbd_config is freed atomic_dec(&config->recv_threads) -> UAF Fix the problem by clearing NBD_RT_BOUND in nbd_genl_disconnect(), so that nbd_genl_reconfigure() will fail.
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: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-02-27 17:58 UTC
CWE
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6820 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: b7aa3d39385dc2d95899f9e379623fef446a2acd , < e70a578487a47d7cf058904141e586684d1c3381 (git)
Affected: b7aa3d39385dc2d95899f9e379623fef446a2acd , < 6bef6222a3f6c7adb6396f77f25a3579d821b09a (git)
Affected: b7aa3d39385dc2d95899f9e379623fef446a2acd , < e3be8862d73cac833e0fb7602636c19c6cb94b11 (git)
Affected: b7aa3d39385dc2d95899f9e379623fef446a2acd , < e7343fa33751cb07c1c56b666bf37cfca357130e (git)
Affected: b7aa3d39385dc2d95899f9e379623fef446a2acd , < d208d2c52b652913b5eefc8ca434b0d6b757f68f (git)
Affected: b7aa3d39385dc2d95899f9e379623fef446a2acd , < a8ee6ecde2b7bfb58c8a3afe8a9d2b848f580739 (git)
Affected: b7aa3d39385dc2d95899f9e379623fef446a2acd , < 9793bd5ae4bdbdb2dde401a3cab94a6bfd05e302 (git)
Affected: b7aa3d39385dc2d95899f9e379623fef446a2acd , < 844b8cdc681612ff24df62cdefddeab5772fadf1 (git)
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Linux Linux Affected: 4.12
Unaffected: 0 , < 4.12 (semver)
Unaffected: 5.4.291 , ≤ 5.4.* (semver)
Unaffected: 5.10.235 , ≤ 5.10.* (semver)
Unaffected: 5.15.179 , ≤ 5.15.* (semver)
Unaffected: 6.1.129 , ≤ 6.1.* (semver)
Unaffected: 6.6.76 , ≤ 6.6.* (semver)
Unaffected: 6.12.13 , ≤ 6.12.* (semver)
Unaffected: 6.13.2 , ≤ 6.13.* (semver)
Unaffected: 6.14 , ≤ * (original_commit_for_fix)
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Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
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Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.7 , < * (custom)
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Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
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Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP Affected: V3.1.7 , < * (custom)
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Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem Affected: 0 , < * (custom)
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Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
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Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.7 , < * (custom)
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnbd: don\u0027t allow reconnect after disconnect\n\nFollowing process can cause nbd_config UAF:\n\n1) grab nbd_config temporarily;\n\n2) nbd_genl_disconnect() flush all recv_work() and release the\ninitial reference:\n\n  nbd_genl_disconnect\n   nbd_disconnect_and_put\n    nbd_disconnect\n     flush_workqueue(nbd-\u003erecv_workq)\n    if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF, ...))\n     nbd_config_put\n     -\u003e due to step 1), reference is still not zero\n\n3) nbd_genl_reconfigure() queue recv_work() again;\n\n  nbd_genl_reconfigure\n   config = nbd_get_config_unlocked(nbd)\n   if (!config)\n   -\u003e succeed\n   if (!test_bit(NBD_RT_BOUND, ...))\n   -\u003e succeed\n   nbd_reconnect_socket\n    queue_work(nbd-\u003erecv_workq, \u0026args-\u003ework)\n\n4) step 1) release the reference;\n\n5) Finially, recv_work() will trigger UAF:\n\n  recv_work\n   nbd_config_put(nbd)\n   -\u003e nbd_config is freed\n   atomic_dec(\u0026config-\u003erecv_threads)\n   -\u003e UAF\n\nFix the problem by clearing NBD_RT_BOUND in nbd_genl_disconnect(), so\nthat nbd_genl_reconfigure() will fail."
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            "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: nbd: no permitir la reconexi\u00f3n despu\u00e9s de la desconexi\u00f3n El siguiente proceso puede causar el nbd_config UAF: 1) grab nbd_config temporarily; 2) nbd_genl_disconnect() flush all recv_work() and release the initial reference: nbd_genl_disconnect nbd_disconnect_and_put nbd_disconnect flush_workqueue(nbd-\u0026gt;recv_workq) if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF, ...)) nbd_config_put -\u0026gt; due to step 1), reference is still not zero 3) nbd_genl_reconfigure() queue recv_work() again; nbd_genl_reconfigure config = nbd_get_config_unlocked(nbd) if (!config) -\u0026gt; succeed if (!test_bit(NBD_RT_BOUND, ...)) -\u0026gt; succeed nbd_reconnect_socket queue_work(nbd-\u0026gt;recv_workq, \u0026amp;args-\u0026gt;work) 4) step 1) release the reference; 5) Finially, recv_work() will trigger UAF: recv_work nbd_config_put(nbd) -\u0026gt; nbd_config is freed atomic_dec(\u0026amp;config-\u0026gt;recv_threads) -\u0026gt; UAF Fix the problem by clearing NBD_RT_BOUND in nbd_genl_disconnect(), so that nbd_genl_reconfigure() will fail. "
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                  "lessThan": "6bef6222a3f6c7adb6396f77f25a3579d821b09a",
                  "status": "affected",
                  "version": "b7aa3d39385dc2d95899f9e379623fef446a2acd",
                  "versionType": "git"
                },
                {
                  "lessThan": "e3be8862d73cac833e0fb7602636c19c6cb94b11",
                  "status": "affected",
                  "version": "b7aa3d39385dc2d95899f9e379623fef446a2acd",
                  "versionType": "git"
                },
                {
                  "lessThan": "e7343fa33751cb07c1c56b666bf37cfca357130e",
                  "status": "affected",
                  "version": "b7aa3d39385dc2d95899f9e379623fef446a2acd",
                  "versionType": "git"
                },
                {
                  "lessThan": "d208d2c52b652913b5eefc8ca434b0d6b757f68f",
                  "status": "affected",
                  "version": "b7aa3d39385dc2d95899f9e379623fef446a2acd",
                  "versionType": "git"
                },
                {
                  "lessThan": "a8ee6ecde2b7bfb58c8a3afe8a9d2b848f580739",
                  "status": "affected",
                  "version": "b7aa3d39385dc2d95899f9e379623fef446a2acd",
                  "versionType": "git"
                },
                {
                  "lessThan": "9793bd5ae4bdbdb2dde401a3cab94a6bfd05e302",
                  "status": "affected",
                  "version": "b7aa3d39385dc2d95899f9e379623fef446a2acd",
                  "versionType": "git"
                },
                {
                  "lessThan": "844b8cdc681612ff24df62cdefddeab5772fadf1",
                  "status": "affected",
                  "version": "b7aa3d39385dc2d95899f9e379623fef446a2acd",
                  "versionType": "git"
                }
              ]
            },
            {
              "defaultStatus": "affected",
              "product": "Linux",
              "programFiles": [
                "drivers/block/nbd.c"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "status": "affected",
                  "version": "4.12"
                },
                {
                  "lessThan": "4.12",
                  "status": "unaffected",
                  "version": "0",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "5.4.*",
                  "status": "unaffected",
                  "version": "5.4.291",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "5.10.*",
                  "status": "unaffected",
                  "version": "5.10.235",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "5.15.*",
                  "status": "unaffected",
                  "version": "5.15.179",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.1.*",
                  "status": "unaffected",
                  "version": "6.1.129",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.6.*",
                  "status": "unaffected",
                  "version": "6.6.76",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.12.*",
                  "status": "unaffected",
                  "version": "6.12.13",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.13.*",
                  "status": "unaffected",
                  "version": "6.13.2",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "*",
                  "status": "unaffected",
                  "version": "6.14",
                  "versionType": "original_commit_for_fix"
                }
              ]
            }
          ],
          "cpeApplicability": [
            {
              "nodes": [
                {
                  "cpeMatch": [
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.4.291",
                      "versionStartIncluding": "4.12",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.10.235",
                      "versionStartIncluding": "4.12",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.15.179",
                      "versionStartIncluding": "4.12",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.1.129",
                      "versionStartIncluding": "4.12",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.6.76",
                      "versionStartIncluding": "4.12",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.12.13",
                      "versionStartIncluding": "4.12",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.13.2",
                      "versionStartIncluding": "4.12",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.14",
                      "versionStartIncluding": "4.12",
                      "vulnerable": true
                    }
                  ],
                  "negate": false,
                  "operator": "OR"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnbd: don\u0027t allow reconnect after disconnect\n\nFollowing process can cause nbd_config UAF:\n\n1) grab nbd_config temporarily;\n\n2) nbd_genl_disconnect() flush all recv_work() and release the\ninitial reference:\n\n  nbd_genl_disconnect\n   nbd_disconnect_and_put\n    nbd_disconnect\n     flush_workqueue(nbd-\u003erecv_workq)\n    if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF, ...))\n     nbd_config_put\n     -\u003e due to step 1), reference is still not zero\n\n3) nbd_genl_reconfigure() queue recv_work() again;\n\n  nbd_genl_reconfigure\n   config = nbd_get_config_unlocked(nbd)\n   if (!config)\n   -\u003e succeed\n   if (!test_bit(NBD_RT_BOUND, ...))\n   -\u003e succeed\n   nbd_reconnect_socket\n    queue_work(nbd-\u003erecv_workq, \u0026args-\u003ework)\n\n4) step 1) release the reference;\n\n5) Finially, recv_work() will trigger UAF:\n\n  recv_work\n   nbd_config_put(nbd)\n   -\u003e nbd_config is freed\n   atomic_dec(\u0026config-\u003erecv_threads)\n   -\u003e UAF\n\nFix the problem by clearing NBD_RT_BOUND in nbd_genl_disconnect(), so\nthat nbd_genl_reconfigure() will fail."
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-05-11T21:05:20.600Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
          },
          "references": [
            {
              "url": "https://git.kernel.org/stable/c/e70a578487a47d7cf058904141e586684d1c3381"
            },
            {
              "url": "https://git.kernel.org/stable/c/6bef6222a3f6c7adb6396f77f25a3579d821b09a"
            },
            {
              "url": "https://git.kernel.org/stable/c/e3be8862d73cac833e0fb7602636c19c6cb94b11"
            },
            {
              "url": "https://git.kernel.org/stable/c/e7343fa33751cb07c1c56b666bf37cfca357130e"
            },
            {
              "url": "https://git.kernel.org/stable/c/d208d2c52b652913b5eefc8ca434b0d6b757f68f"
            },
            {
              "url": "https://git.kernel.org/stable/c/a8ee6ecde2b7bfb58c8a3afe8a9d2b848f580739"
            },
            {
              "url": "https://git.kernel.org/stable/c/9793bd5ae4bdbdb2dde401a3cab94a6bfd05e302"
            },
            {
              "url": "https://git.kernel.org/stable/c/844b8cdc681612ff24df62cdefddeab5772fadf1"
            }
          ],
          "title": "nbd: don\u0027t allow reconnect after disconnect",
          "x_generator": {
            "engine": "bippy-1.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2025-21731",
        "datePublished": "2025-02-27T02:07:35.927Z",
        "dateReserved": "2024-12-29T08:45:45.755Z",
        "dateUpdated": "2026-09-08T08:40:26.587Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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