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GHSA-7C5C-GPH2-XXG8

Vulnerability from github – Published: 2026-09-25 12:31 – Updated: 2026-09-25 15:31

Details

In the Linux kernel, the following vulnerability has been resolved:

mptcp: close race between scheduler and state change

The mptcp scheduler may race with subflow sockets state change: data transmission on the selected socket may fail and a later release could try to use mss_now reset to 0 for a divide operation.

Address the issue by explicitly checking for the critical scenario.

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-97523"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-25T11:17:02Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: close race between scheduler and state change\n\nThe mptcp scheduler may race with subflow sockets state change: data\ntransmission on the selected socket may fail and a later release could\ntry to use mss_now reset to 0 for a divide operation.\n\nAddress the issue by explicitly checking for the critical scenario.",
  "id": "GHSA-7c5c-gph2-xxg8",
  "modified": "2026-09-25T15:31:41Z",
  "published": "2026-09-25T12:31:22Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-97523"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/42064de57fb83231fcc89663a94885f228a1ee53"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4c856f3c151a2f3fa237caa651c44015916ca584"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8f11430d51ff8365bc51b670bc3002b65ae4c6b7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a09c87abf10a0a7e203137c75b5381aa63d9b31d"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-97523 (GCVE-0-2026-97523)

Vulnerability from cvelistv5 – Published: 2026-09-25 10:21 – Updated: 2026-09-25 14:41

Title

mptcp: close race between scheduler and state change

Summary

In the Linux kernel, the following vulnerability has been resolved: mptcp: close race between scheduler and state change The mptcp scheduler may race with subflow sockets state change: data transmission on the selected socket may fail and a later release could try to use mss_now reset to 0 for a divide operation. Address the issue by explicitly checking for the critical scenario.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/8f11430d51ff8365b…
https://git.kernel.org/stable/c/a09c87abf10a0a7e2…
https://git.kernel.org/stable/c/4c856f3c151a2f3fa…
https://git.kernel.org/stable/c/42064de57fb83231f…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: c886d70286bf3ad411eb3d689328a67f7102c6ae , < 8f11430d51ff8365bc51b670bc3002b65ae4c6b7 (git) Affected: c886d70286bf3ad411eb3d689328a67f7102c6ae , < a09c87abf10a0a7e203137c75b5381aa63d9b31d (git) Affected: c886d70286bf3ad411eb3d689328a67f7102c6ae , < 4c856f3c151a2f3fa237caa651c44015916ca584 (git) Affected: c886d70286bf3ad411eb3d689328a67f7102c6ae , < 42064de57fb83231fcc89663a94885f228a1ee53 (git) Affected: fb9c73ef2ac2ec816efdc8b9267bc04e1369c20b (git) Affected: 8caf5c15b5288d52d9c89374d6c10fa32ee84ec5 (git) Affected: 5.15.190 , < 5.16 (semver) Affected: 5.19.4 , < 5.20 (semver)
Linux	Linux	Affected: 6.0 Unaffected: 0 , < 6.0 (semver) Unaffected: 6.12.111 , ≤ 6.12.* (semver) Unaffected: 6.18.53 , ≤ 6.18.* (semver) Unaffected: 7.2.7 , ≤ 7.2.* (semver) Unaffected: 7.3-rc4 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/protocol.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "8f11430d51ff8365bc51b670bc3002b65ae4c6b7",
              "status": "affected",
              "version": "c886d70286bf3ad411eb3d689328a67f7102c6ae",
              "versionType": "git"
            },
            {
              "lessThan": "a09c87abf10a0a7e203137c75b5381aa63d9b31d",
              "status": "affected",
              "version": "c886d70286bf3ad411eb3d689328a67f7102c6ae",
              "versionType": "git"
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              "lessThan": "4c856f3c151a2f3fa237caa651c44015916ca584",
              "status": "affected",
              "version": "c886d70286bf3ad411eb3d689328a67f7102c6ae",
              "versionType": "git"
            },
            {
              "lessThan": "42064de57fb83231fcc89663a94885f228a1ee53",
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              "version": "c886d70286bf3ad411eb3d689328a67f7102c6ae",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "fb9c73ef2ac2ec816efdc8b9267bc04e1369c20b",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "8caf5c15b5288d52d9c89374d6c10fa32ee84ec5",
              "versionType": "git"
            },
            {
              "lessThan": "5.16",
              "status": "affected",
              "version": "5.15.190",
              "versionType": "semver"
            },
            {
              "lessThan": "5.20",
              "status": "affected",
              "version": "5.19.4",
              "versionType": "semver"
            }
          ]
        },
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          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/protocol.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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          "versions": [
            {
              "status": "affected",
              "version": "6.0"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc4",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.111",
                  "versionStartIncluding": "6.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.53",
                  "versionStartIncluding": "6.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "5.19.4",
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              ],
              "negate": false,
              "operator": "OR"
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      "descriptions": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: close race between scheduler and state change\n\nThe mptcp scheduler may race with subflow sockets state change: data\ntransmission on the selected socket may fail and a later release could\ntry to use mss_now reset to 0 for a divide operation.\n\nAddress the issue by explicitly checking for the critical scenario."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - mptcp_push_release is reached from __mptcp_push_pending after mptcp_sched_get_send. A remote MPTCP peer changes the selected subflow\u0027s sk_state via TCP RST/FIN (tcp_v4_rcv/tcp_rcv_established/tcp_reset) without the msk lock, and a DSS DATA_ACK (mptcp_incoming_options\u2192ack_update_msk) sets MPTCP_PUSH_PENDING so mptcp_release_cb calls that push.\nAC:L - The attacker creates both halves of the race: they induce __mptcp_push_pending (DSS DATA_ACK, or eliciting mptcp_sendmsg) so mptcp_subflow_get_send snapshots __tcp_can_send without the ssk lock, then RST/FIN/MP_FAIL that subflow before lock_sock; the window is attacker-timed and retryable, not an uninfluencable layout.\nPR:N - Completing MP_CAPABLE to an IPPROTO_MPTCP listener needs no account or capability; net.mptcp.enabled defaults to 1 in mptcp pernet init, and tcp_rcv_established/mptcp_incoming_options apply no application credentials before the DATA_ACK and RST/FIN that cause this race.\nUI:N - The attacker sends the DATA_ACK and RST/FIN themselves and supplies the request that makes the service call mptcp_sendmsg; no victim mount, click, or extra confirmation is required.\nS:U - The divide-error runs in tcp_tso_autosize/tcp_set_skb_tso_segs on the host kernel MPTCP/TCP socket; it does not cross a VM, IOMMU, or sandbox boundary.\nC:N - When __tcp_can_send fails in mptcp_sendmsg_frag, info-\u003emss_now stays 0 and tcp_push divides by zero; that CPU exception does not read freed objects or out-of-range kernel memory.\nI:N - tcp_write_xmit aborts on the divide in tcp_tso_autosize/tcp_set_skb_tso_segs before modifying TCP control blocks or packet contents; this is not an OOB/UAF write or control-flow hijack.\nA:H - bytes/mss_now in tcp_tso_autosize and DIV_ROUND_UP(skb-\u003elen, mss_now) in tcp_set_skb_tso_segs raise a kernel divide-error oops/panic from mptcp_push_release, and the attacker can repeat it across MPTCP connections."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-25T14:41:04.318Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
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          "url": "https://git.kernel.org/stable/c/42064de57fb83231fcc89663a94885f228a1ee53"
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      "title": "mptcp: close race between scheduler and state change",
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97523",
    "datePublished": "2026-09-25T10:21:27.042Z",
    "dateReserved": "2026-09-24T16:01:01.152Z",
    "dateUpdated": "2026-09-25T14:41:04.318Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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GHSA-7C5C-GPH2-XXG8

CVE-2026-97523 (GCVE-0-2026-97523)

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