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CVE-2023-54085 (GCVE-0-2023-54085)

Vulnerability from cvelistv5 – Published: 2025-12-24 13:06 – Updated: 2026-08-05 09:17
VLAI
Title
mptcp: fix NULL pointer dereference on fastopen early fallback
Summary
In the Linux kernel, the following vulnerability has been resolved: mptcp: fix NULL pointer dereference on fastopen early fallback In case of early fallback to TCP, subflow_syn_recv_sock() deletes the subflow context before returning the newly allocated sock to the caller. The fastopen path does not cope with the above unconditionally dereferencing the subflow context.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 36b122baf6a8bd46b4a591f12f4ed17b22257408 , < 95135835519b0ab931c39908b2c99e9fb3c9068b (git)
Affected: 36b122baf6a8bd46b4a591f12f4ed17b22257408 , < c0ff6f6da66a7791a32c0234388b1bdc00244917 (git)
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Linux Linux Affected: 6.2
Unaffected: 0 , < 6.2 (semver)
Unaffected: 6.2.12 , ≤ 6.2.* (semver)
Unaffected: 6.3 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/fastopen.c"
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        }
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      "metrics": [
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
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              "value": "AV:N - The crash is triggered entirely by a received TCP SYN packet with fastopen data arriving at an MPTCP listening socket, processed in the TCP input path (`tcp_conn_request`). Any routable remote peer can reach it.\nAC:L - The attacker fully controls the trigger \u2014 a TFO SYN with data and no MPTCP options deterministically causes `subflow_ulp_clone()` to drop the context and `subflow_prep_synack()` to pass NULL; there is no race, no memory-layout dependency, and the TFO cookie is freely obtainable from a prior normal connection.\nPR:N - No credentials or prior authentication are required; the fault occurs during connection establishment, before any application-level handshake, on a socket that has not yet been accepted.\nUI:N - Exploitation requires only that the attacker send packets to the listening port; no action by any local user or administrator is needed at attack time.\nS:U - The NULL dereference occurs in the kernel\u0027s own network stack and affects only the kernel\u0027s security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:N - The faulting access is a load of `subflow-\u003etcp_sock` at a fixed small offset from NULL, which aborts immediately; no attacker-controlled data is read back or disclosed.\nI:N - Execution aborts on the first NULL load before `subflow-\u003eis_mptfo = 1` or any queue manipulation, so no kernel memory is modified and no control-flow primitive is obtained.\nA:H - The dereference at NULL+~208 bytes is always unmapped and occurs in NET_RX softirq context, so `oops_end()` takes the `in_interrupt()` path and issues `panic(\"Fatal exception in interrupt\")` \u2014 a guaranteed, remotely repeatable full system crash."
            }
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      "providerMetadata": {
        "dateUpdated": "2026-08-05T09:17:06.087Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/95135835519b0ab931c39908b2c99e9fb3c9068b"
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        {
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    "cveId": "CVE-2023-54085",
    "datePublished": "2025-12-24T13:06:16.161Z",
    "dateReserved": "2025-12-24T13:02:52.515Z",
    "dateUpdated": "2026-08-05T09:17:06.087Z",
    "state": "PUBLISHED"
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: fix NULL pointer dereference on fastopen early fallback\n\nIn case of early fallback to TCP, subflow_syn_recv_sock() deletes\nthe subflow context before returning the newly allocated sock to\nthe caller.\n\nThe fastopen path does not cope with the above unconditionally\ndereferencing the subflow context."
          }
        ],
        "id": "CVE-2023-54085",
        "lastModified": "2026-08-04T10:19:28.240",
        "metrics": {
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                "baseScore": 7.5,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
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              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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      "cve": "CVE-2023-54085",
      "id": "CVE-2023-54085",
      "initial_release_date": "2023-01-01T00:00:00+00:00",
      "product_status:known_affected": "108",
      "product_status:known_not_affected": "166",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Linux kernel: Denial of Service due to NULL pointer dereference in mptcp fastopen",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2023/cve-2023-54085.json",
      "version": "3"
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      "current_release_date": "2026-08-28T02:25:18Z",
      "cve": "CVE-2023-54085",
      "id": "CVE-2023-54085",
      "initial_release_date": "2025-12-25T00:55:59Z",
      "product_status:known_not_affected": "459",
      "product_status:recommended": "29",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2023-54085",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2023-54085.json",
      "version": "13"
    }
  }
}



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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

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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.


Detection rules are retrieved from Rulezet.


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