CVE-2026-43378 (GCVE-0-2026-43378)
Vulnerability from cvelistv5
Published
2026-05-08 14:21
Modified
2026-08-05 12:27
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: server: fix use-after-free in smb2_open() The opinfo pointer obtained via rcu_dereference(fp->f_opinfo) is dereferenced after rcu_read_unlock(), creating a use-after-free window.
References
Impacted products
Vendor Product Version
Linux Linux Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smb2pdu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e1b21e6066615e7d3d3a7aa2677e415e563fd7cc",
              "status": "affected",
              "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9",
              "versionType": "git"
            },
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              "versionType": "git"
            },
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              "status": "affected",
              "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9",
              "versionType": "git"
            },
            {
              "lessThan": "190e5f808e8058640b408ccfed25440b441a718a",
              "status": "affected",
              "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9",
              "versionType": "git"
            },
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              "lessThan": "1e689a56173827669a35da7cb2a3c78ed5c53680",
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              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smb2pdu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.15"
            },
            {
              "lessThan": "5.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.167",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.130",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.78",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.19",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.167",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.130",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.78",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.19",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.9",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: server: fix use-after-free in smb2_open()\n\nThe opinfo pointer obtained via rcu_dereference(fp-\u003ef_opinfo) is\ndereferenced after rcu_read_unlock(), creating a use-after-free\nwindow."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable path is ksmbd\u0027s SMB2 CREATE handler, reachable over the SMB server network listener on TCP/445 or SMB Direct. A remote client can drive the request path to `smb2_open()`.\nAC:L - The bug is a UAF window around concurrent oplock/lease state changes, and an attacker can create concurrent SMB opens/lease breaks using multiple requests or connections. Under the rule to choose higher severity when uncertain, this is Low complexity.\nPR:N - `SMB2_CREATE` requires a valid session and tree connection, but ksmbd supports guest/anonymous SMB sessions and guest shares in a reasonable deployment. In that scenario no prior credentials are required.\nUI:N - Exploitation is driven entirely by network SMB requests. No victim user action is required after the server is running.\nS:U - The vulnerability is in the kernel SMB server and impacts the same host kernel security authority. It does not inherently cross a VM, hypervisor, or separate security scope boundary.\nC:H - The flaw is a use-after-free of `struct oplock_info` and its lease data after RCU protection is dropped. Kernel UAF memory corruption can be leveraged for high-impact information disclosure.\nI:H - The dangling `oplock_info` pointer can be used after free while building the SMB2 CREATE response, creating exploitable kernel memory corruption. UAFs are treated as capable of arbitrary write or control-flow impact.\nA:H - A remotely triggerable kernel UAF can cause an oops, panic, or service crash. Repeated SMB requests can make the availability impact high."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:27:38.612Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e1b21e6066615e7d3d3a7aa2677e415e563fd7cc"
        },
        {
          "url": "https://git.kernel.org/stable/c/b720c84087cb547f23ce03eab93568c1769e4556"
        },
        {
          "url": "https://git.kernel.org/stable/c/54b48ae83de8bb06e65079d96368efe359d4909c"
        },
        {
          "url": "https://git.kernel.org/stable/c/8f5b1a7cb009a93c48e9e334a2f59a660f9afc07"
        },
        {
          "url": "https://git.kernel.org/stable/c/190e5f808e8058640b408ccfed25440b441a718a"
        },
        {
          "url": "https://git.kernel.org/stable/c/1e689a56173827669a35da7cb2a3c78ed5c53680"
        }
      ],
      "title": "smb: server: fix use-after-free in smb2_open()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43378",
    "datePublished": "2026-05-08T14:21:27.319Z",
    "dateReserved": "2026-05-01T14:12:56.006Z",
    "dateUpdated": "2026-08-05T12:27:38.612Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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