Vulnerability-Lookup

GHSA-232G-622W-PRRG

Vulnerability from github – Published: 2026-10-18 15:30 – Updated: 2026-10-18 15:30

Details

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

mptcp: options: fix uninit-value in mptcp_write_data_fin

When sending a DATA_FIN without data, and because the DATA_FIN occupies 1 octet of the connection-level sequence space [1], it is then required to add a DSS mapping with specific values.

If the checksum has been negotiated, it also needs to be computed, and included in the outgoing packet, and thus the initial csum data needs to be reset to 0 as well. This is no longer the case since commit cfcceb7a39fc ("tcp: shrink per-packet memset in __tcp_transmit_skb()"), because the whole ext_copy structure is no longer zeroed by default.

This seems to be the only case where use_map is changed and set afterwards, so initialising the csum field only in this case, along with other fields for this specific case.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98438"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-18T15:16:53Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: options: fix uninit-value in mptcp_write_data_fin\n\nWhen sending a DATA_FIN without data, and because the DATA_FIN occupies\n1 octet of the connection-level sequence space [1], it is then required\nto add a DSS mapping with specific values.\n\nIf the checksum has been negotiated, it also needs to be computed, and\nincluded in the outgoing packet, and thus the initial csum data needs to\nbe reset to 0 as well. This is no longer the case since commit\ncfcceb7a39fc (\"tcp: shrink per-packet memset in __tcp_transmit_skb()\"),\nbecause the whole ext_copy structure is no longer zeroed by default.\n\nThis seems to be the only case where use_map is changed and set\nafterwards, so initialising the csum field only in this case, along with\nother fields for this specific case.",
  "id": "GHSA-232g-622w-prrg",
  "modified": "2026-10-18T15:30:32Z",
  "published": "2026-10-18T15:30:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98438"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9a682067dd7b9dce6b94a0a05661dcc921446402"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b110f1dd6cb6a9930503354a01a315e0a821eaa7"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-98438 (GCVE-0-2026-98438)

Vulnerability from cvelistv5 – Published: 2026-10-18 14:45 – Updated: 2026-10-19 09:19

Title

mptcp: options: fix uninit-value in mptcp_write_data_fin

Summary

In the Linux kernel, the following vulnerability has been resolved: mptcp: options: fix uninit-value in mptcp_write_data_fin When sending a DATA_FIN without data, and because the DATA_FIN occupies 1 octet of the connection-level sequence space [1], it is then required to add a DSS mapping with specific values. If the checksum has been negotiated, it also needs to be computed, and included in the outgoing packet, and thus the initial csum data needs to be reset to 0 as well. This is no longer the case since commit cfcceb7a39fc ("tcp: shrink per-packet memset in __tcp_transmit_skb()"), because the whole ext_copy structure is no longer zeroed by default. This seems to be the only case where use_map is changed and set afterwards, so initialising the csum field only in this case, along with other fields for this specific case.

Severity

No CVSS data available.

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 7056 records in the last 180 days details

References

2 references

URL	Tags
https://git.kernel.org/stable/c/9a682067dd7b9dce6…
https://git.kernel.org/stable/c/b110f1dd6cb6a9930…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: cfcceb7a39fc10a6f896af8229bf81d96acb22cc , < 9a682067dd7b9dce6b94a0a05661dcc921446402 (git) Affected: cfcceb7a39fc10a6f896af8229bf81d96acb22cc , < b110f1dd6cb6a9930503354a01a315e0a821eaa7 (git)
Linux	Linux	Affected: 7.1 Unaffected: 0 , < 7.1 (semver) Unaffected: 7.2.7 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix)

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JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/options.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
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              "versionType": "git"
            },
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              "lessThan": "b110f1dd6cb6a9930503354a01a315e0a821eaa7",
              "status": "affected",
              "version": "cfcceb7a39fc10a6f896af8229bf81d96acb22cc",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/options.c"
          ],
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
                {
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                  "versionStartIncluding": "7.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "7.1",
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                }
              ],
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              "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: options: fix uninit-value in mptcp_write_data_fin\n\nWhen sending a DATA_FIN without data, and because the DATA_FIN occupies\n1 octet of the connection-level sequence space [1], it is then required\nto add a DSS mapping with specific values.\n\nIf the checksum has been negotiated, it also needs to be computed, and\nincluded in the outgoing packet, and thus the initial csum data needs to\nbe reset to 0 as well. This is no longer the case since commit\ncfcceb7a39fc (\"tcp: shrink per-packet memset in __tcp_transmit_skb()\"),\nbecause the whole ext_copy structure is no longer zeroed by default.\n\nThis seems to be the only case where use_map is changed and set\nafterwards, so initialising the csum field only in this case, along with\nother fields for this specific case."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:19:34.132Z",
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    "datePublished": "2026-10-18T14:45:27.288Z",
    "dateReserved": "2026-09-25T10:25:14.349Z",
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    "state": "PUBLISHED"
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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.

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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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