CVE-2026-64387 (GCVE-0-2026-64387)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:50 – Updated: 2026-08-05 12:41
VLAI
Title
smb: client: fix query directory replay double-free
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix query directory replay double-free A response-bearing attempt can return a replayable error and free its response buffer. If SMB2_query_directory_init() fails before the next send, cleanup retains the previous buffer type and frees that response again. Reset response bookkeeping before each attempt to prevent the stale free.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 433042a91f9373241307725b52de573933ffedbf , < 3409aedf3c81a810243da94164f6621c9d205c98 (git)
Affected: 4f1fffa2376922f3d1d506e49c0fd445b023a28e , < 1665f25b1dea30bf2d02e16245d203a944c9d994 (git)
Affected: 4f1fffa2376922f3d1d506e49c0fd445b023a28e , < 00b0fa425941438b664950a8ee65dfba2def4336 (git)
Affected: 4f1fffa2376922f3d1d506e49c0fd445b023a28e , < 3317a5d015fca976475aa71df224056777316fde (git)
Affected: 4f1fffa2376922f3d1d506e49c0fd445b023a28e , < 9647492b5e41954be59d5157eddbcd4cdc1656f7 (git)
Affected: 6.6.32 , < 6.6.145 (semver)
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Linux Linux Affected: 6.8
Unaffected: 0 , < 6.8 (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.96 , ≤ 6.12.* (semver)
Unaffected: 6.18.39 , ≤ 6.18.* (semver)
Unaffected: 7.1.4 , ≤ 7.1.* (semver)
Unaffected: 7.2-rc1 , ≤ * (original_commit_for_fix)
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{
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          "programFiles": [
            "fs/smb/client/smb2pdu.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix query directory replay double-free\n\nA response-bearing attempt can return a replayable error and free its\nresponse buffer. If SMB2_query_directory_init() fails before the next send,\ncleanup retains the previous buffer type and frees that response again.\n\nReset response bookkeeping before each attempt to prevent the stale free."
        }
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            "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"
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              "lang": "en",
              "value": "AV:N - A malicious remote SMB server can trigger the flaw through crafted responses to SMB2 QUERY_DIRECTORY requests over the established network connection.\nAC:L - On a hard/retrans-enabled mount, the server controls the replayable error and can repeatedly induce disconnect/reconnect conditions before request reinitialization, without relying on an uncontrollable race.\nPR:N - The attacker needs no account or privilege on the client; the client authenticates to the attacker-controlled SMB server, and ordinary accessible-share enumeration reaches the code.\nUI:N - In a reasonable auto-mounted deployment, routine directory enumeration can be performed automatically by a daemon or application without human participation.\nS:U - The corruption occurs within the client kernel and compromises resources governed by that same kernel security authority.\nC:H - Double-freeing the attacker-influenced CIFS response object can poison the slab freelist or create overlapping allocations, providing UAF-style primitives capable of exposing arbitrary kernel memory.\nI:H - Allocator corruption and aliased CIFS buffers can enable attacker-influenced writes and potentially control-flow hijacking or kernel code execution.\nA:H - The double-free can immediately trigger allocator diagnostics, an oops, or a kernel panic, and corrupted freelists can cause subsequent fatal faults."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:41:24.033Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "title": "smb: client: fix query directory replay double-free",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64387",
    "datePublished": "2026-07-25T08:50:35.543Z",
    "dateReserved": "2026-07-19T15:36:31.784Z",
    "dateUpdated": "2026-08-05T12:41:24.033Z",
    "state": "PUBLISHED"
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    },
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      "cve": "CVE-2026-64387",
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      "initial_release_date": "2026-07-26T01:08:44.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "smb: client: fix query directory replay double-free",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-64387.json",
      "version": "2"
    },
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    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-07-29T13:12:17+00:00",
      "cve": "CVE-2026-64387",
      "id": "CVE-2026-64387",
      "initial_release_date": "2026-07-25T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: smb: client: fix query directory replay double-free",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64387.json",
      "version": "3"
    }
  }
}



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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.