CVE-2026-64386 (GCVE-0-2026-64386)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:50 – Updated: 2026-08-05 12:41
VLAI
Title
smb: client: fix query_info() replay double-free
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix query_info() replay double-free A response-bearing attempt can return a replayable error and free its response buffer. If SMB2_query_info_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 , < 100fb7c455fa86d248b8bd7bb9de757c192870b4 (git)
Affected: 4f1fffa2376922f3d1d506e49c0fd445b023a28e , < 3c81dda84799f76b42aec598564316e2964440db (git)
Affected: 4f1fffa2376922f3d1d506e49c0fd445b023a28e , < f1add4acb656f5a82806a1ab0e63fed3d8b1bfca (git)
Affected: 4f1fffa2376922f3d1d506e49c0fd445b023a28e , < 89234773e8348918111aa15f6922b58cf3843364 (git)
Affected: 4f1fffa2376922f3d1d506e49c0fd445b023a28e , < 2a88561d66eb855813cf004a0abe648bbb17de5e (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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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix query_info() replay double-free\n\nA response-bearing attempt can return a replayable error and free its\nresponse buffer. If SMB2_query_info_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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      "metrics": [
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            "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 or compromised SMB2/3 server can remotely return a response-bearing replayable error and manipulate the subsequent connection state, reaching the vulnerable client over TCP.\nAC:L - The server controls the error response, disconnect, and reconnection sequence and can repeat it until the stale free occurs. Replay-enabled hard or retrans-configured SMB mounts are a reasonable deployment.\nPR:N - The malicious SMB peer needs no privileges or credentials on the client; SMB session setup authenticates the client to the server, not the attacker to the victim kernel.\nUI:N - Once the share is mounted, ordinary or automated file and metadata operations issue query-info requests, and exploitation requires no human action during the crafted response and reconnect sequence.\nS:U - The corruption and resulting impacts occur within the same Linux kernel security authority, without crossing a VM, sandbox, or IOMMU boundary.\nC:H - The double-free corrupts SMB response-buffer slab and mempool state, enabling aliased or use-after-free buffers that can be leveraged to expose kernel memory.\nI:H - Allocator freelist corruption and reuse of one buffer by concurrent SMB operations can provide attacker-controlled modification of live kernel memory and support control-flow hijacking.\nA:H - The repeated free can immediately cause allocator corruption, a BUG, kernel oops, or panic, and the malicious server can trigger the sequence repeatedly."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:41:22.958Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/2a88561d66eb855813cf004a0abe648bbb17de5e"
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      "title": "smb: client: fix query_info() replay double-free",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64386",
    "datePublished": "2026-07-25T08:50:34.729Z",
    "dateReserved": "2026-07-19T15:36:31.784Z",
    "dateUpdated": "2026-08-05T12:41:22.958Z",
    "state": "PUBLISHED"
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      "percentile": "0.3746"
    },
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      "id": "msrc_CVE-2026-64386",
      "initial_release_date": "2026-07-26T01:06:25.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "smb: client: fix query_info() replay double-free",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-64386.json",
      "version": "2"
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    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-08-02T21:53:41+00:00",
      "cve": "CVE-2026-64386",
      "id": "CVE-2026-64386",
      "initial_release_date": "2026-07-25T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "91",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: smb: client: fix query_info() replay double-free",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64386.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.