CVE-2026-31609 (GCVE-0-2026-31609)

Vulnerability from cvelistv5 – Published: 2026-04-24 14:42 – Updated: 2026-08-05 12:23
VLAI
Title
smb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush() smbd_send_batch_flush() already calls smbd_free_send_io(), so we should not call it again after smbd_post_send() moved it to the batch list.
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: cca0526ef2344cab6944d7f441fc24e152da031b , < a9940dcbe5cb92482c04efc7341039ddf7dbf607 (git)
Affected: 37b5c06956183b65e6808b509cf637632016cdf7 , < 22b7c1c619d808aec4cad3dc42103345e370d107 (git)
Affected: 21538121efe6c8c5b51c742fa02cbe820bc48714 , < f9a162c2bbcd0ac85bd07c5b37cf20286048b65c (git)
Affected: 21538121efe6c8c5b51c742fa02cbe820bc48714 , < 27b7c3e916218b5eb2ee350211140e961bfc49be (git)
Affected: 6.18.11 , < 6.18.24 (semver)
Affected: 6.19.1 , < 6.19.14 (semver)
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Linux Linux Affected: 7.0
Unaffected: 0 , < 7.0 (semver)
Unaffected: 6.18.24 , ≤ 6.18.* (semver)
Unaffected: 6.19.14 , ≤ 6.19.* (semver)
Unaffected: 7.0.1 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
Create a notification for this product.
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{
  "containers": {
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        {
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          "product": "Linux",
          "programFiles": [
            "fs/smb/client/smbdirect.c"
          ],
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          ],
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              "versionType": "semver"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()\n\nsmbd_send_batch_flush() already calls smbd_free_send_io(),\nso we should not call it again after smbd_post_send()\nmoved it to the batch list."
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              "value": "AV:N - The vulnerable path is in the SMB client SMB Direct/RDMA transport and processes protocol events from a remote SMB Direct peer over the network.\nAC:L - A malicious peer can request immediate empty responses and then disrupt the RDMA connection to drive the post-send error path; the trigger is repeatable and does not depend on conditions outside attacker influence.\nPR:N - The attacker is the remote SMB Direct peer/server and does not need privileges on the vulnerable client system or authenticated local access.\nUI:N - In a reasonable deployment with an existing or automatically established SMB Direct mount, the remote peer can trigger the bug through protocol traffic and disconnect timing without further user action.\nS:U - The corruption occurs in the client kernel and impacts the same operating-system security authority, with no VM, IOMMU, or sandbox boundary crossing identified.\nC:H - This is a kernel heap double-free of an SMB Direct send object; as memory corruption, it can plausibly be shaped into use-after-free behavior and kernel memory disclosure.\nI:H - The double-free corrupts kernel allocator state for objects used in RDMA send handling and can plausibly be leveraged for arbitrary kernel memory modification or code execution.\nA:H - Even without full exploitation, the double-free can trigger allocator corruption, warnings, oops, panic, or connection teardown, causing high availability impact."
            }
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:23:48.014Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
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        },
        {
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        },
        {
          "url": "https://git.kernel.org/stable/c/27b7c3e916218b5eb2ee350211140e961bfc49be"
        }
      ],
      "title": "smb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()",
      "x_generator": {
        "engine": "bippy-1.2.0"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31609",
    "datePublished": "2026-04-24T14:42:30.797Z",
    "dateReserved": "2026-03-09T15:48:24.122Z",
    "dateUpdated": "2026-08-05T12:23:48.014Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "percentile": "0.37742"
    },
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      "initial_release_date": "2026-04-02T00:00:00.000Z",
      "product_status:fixed": "2",
      "product_status:known_affected": "3",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "smb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-31609.json",
      "version": "5"
    },
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-02T17:14:42+00:00",
      "cve": "CVE-2026-31609",
      "id": "CVE-2026-31609",
      "initial_release_date": "2026-04-24T00:00:00+00:00",
      "product_status:known_affected": "260",
      "product_status:known_not_affected": "14",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: smb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31609.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-08-06T01:24:16Z",
      "cve": "CVE-2026-31609",
      "id": "CVE-2026-31609",
      "initial_release_date": "2026-04-25T01:38:06Z",
      "product_status:known_not_affected": "315",
      "product_status:recommended": "4",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-31609",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-31609.json",
      "version": "9"
    }
  }
}



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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.