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CVE-2026-31608 (GCVE-0-2026-31608)

Vulnerability from cvelistv5 – Published: 2026-04-24 14:42 – Updated: 2026-08-05 12:23
VLAI
Title
smb: server: avoid double-free in smb_direct_free_sendmsg after smb_direct_flush_send_list()
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: server: avoid double-free in smb_direct_free_sendmsg after smb_direct_flush_send_list() smb_direct_flush_send_list() already calls smb_direct_free_sendmsg(), so we should not call it again after post_sendmsg() 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 CPE status
Linux Linux Affected: 5ef18a2e66f2f33fdac64437bddfb9fe6389fdc7 , < 6968c91fab05b8fc4d6700e0cf34472bb422df25 (git)
Affected: 79242e7b6bc63efec28b7c235bc320806afce6c0 , < 2ba03f46132b0d1a7bafb86e1ef61951a2254023 (git)
Affected: 34abd408c8ba24d7c97bd02ba874d8c714f49db1 , < 830de6eeb9db4cb7e758201fb99328ef4ca4b032 (git)
Affected: 34abd408c8ba24d7c97bd02ba874d8c714f49db1 , < 84ff995ae826aa6bbcc6c7b9ea569ff67c021d72 (git)
Affected: 6.18.11 , < 6.18.24 (semver)
Affected: 6.19.1 , < 6.19.14 (semver)
guessed Create a notification for this product.
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)
guessed Create a notification for this product.
Show details on NVD website
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{
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          "product": "Linux",
          "programFiles": [
            "fs/smb/server/transport_rdma.c"
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      "metrics": [
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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",
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              "value": "AV:N - SMB Direct in ksmbd is exposed over RDMA network listeners on SMB-related ports, and a remote RDMA-capable peer can reach the vulnerable send path. The affected subsystem is an in-kernel SMB server transport, so the defensible vector is Network.\nAC:L - The attacker can establish an SMB Direct connection, request immediate/credit responses, and induce send failure by controlling the peer connection state. Any timing involved is attacker-controlled and repeatable, so complexity is Low.\nPR:N - The vulnerable path is reachable after RDMA/SMB Direct transport negotiation and before SMB user authentication. No valid SMB session or credentials are required to trigger the lower transport credit/keepalive send path.\nUI:N - Exploitation only requires network interaction with the listening ksmbd SMB Direct service. No victim user action is needed.\nS:U - The corruption occurs within the kernel handling the ksmbd transport and impacts the same kernel security authority. This is not a VM escape, sandbox boundary crossing, or separate security scope.\nC:H - The bug is a kernel heap double-free of an SMB Direct send object, which can create use-after-free or overlapping-allocation conditions. Such memory corruption can reasonably be leveraged for kernel memory disclosure, so Confidentiality is High.\nI:H - A double-free in kernel heap/mempool state can be exploitable for controlled memory corruption and potentially control-flow or data modification. Following the higher-severity rule for memory corruption, Integrity is High.\nA:H - At minimum, the double-free can corrupt allocator state or trigger kernel warnings/oops/panic during send teardown. A remote unauthenticated peer can repeatedly trigger the condition, so Availability is High."
            }
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        "dateUpdated": "2026-08-05T12:23:46.955Z",
        "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/84ff995ae826aa6bbcc6c7b9ea569ff67c021d72"
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      ],
      "title": "smb: server: avoid double-free in smb_direct_free_sendmsg after smb_direct_flush_send_list()",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31608",
    "datePublished": "2026-04-24T14:42:30.137Z",
    "dateReserved": "2026-03-09T15:48:24.122Z",
    "dateUpdated": "2026-08-05T12:23:46.955Z",
    "state": "PUBLISHED"
  },
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      "date": "2026-09-16",
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      "percentile": "0.38734"
    },
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      "product_status:fixed": "1",
      "product_status:known_affected": "1",
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      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "smb: server: avoid double-free in smb_direct_free_sendmsg after smb_direct_flush_send_list()",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-31608.json",
      "version": "6"
    },
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    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-06-28T11:34:58+00:00",
      "cve": "CVE-2026-31608",
      "id": "CVE-2026-31608",
      "initial_release_date": "2026-04-24T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: smb: server: avoid double-free in smb_direct_free_sendmsg after smb_direct_flush_send_list()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31608.json",
      "version": "3"
    },
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      "cve": "CVE-2026-31608",
      "id": "CVE-2026-31608",
      "initial_release_date": "2026-04-25T01:38:07Z",
      "product_status:known_not_affected": "315",
      "product_status:recommended": "4",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-31608",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-31608.json",
      "version": "7"
    }
  }
}



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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.

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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.


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