Vulnerability-Lookup

GHSA-97JQ-2G8V-56HQ

Vulnerability from github – Published: 2026-09-17 18:31 – Updated: 2026-09-17 18:31

Details

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

net/sched: fq: clamp quantum and initial_quantum in change path

The fq change path accepts TCA_FQ_QUANTUM in [1, INT_MAX] and TCA_FQ_INITIAL_QUANTUM up to INT_MAX, while fq_init() already clamps to [1, 1<<20]. A user can override the init clamp via tc qdisc change, restoring the small-quantum deficit spin that the init clamp prevents.

Narrow iq_range.max to 1<<20 so TCA_FQ_INITIAL_QUANTUM is rejected at parse time. Clamp TCA_FQ_QUANTUM to [256, 1<<20] in fq_change() and fq_init() quantum to [256, 1<<20] for tiny-MTU devices.

Conditions to recreate the bug: CONFIG_NET_SCH_FQ=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices).

tc qdisc add dev dummy0 root fq tc qdisc change dev dummy0 root fq quantum 1 stab data 32768 size_log 15 cell_log 0

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{
  "affected": [],
  "aliases": [
    "CVE-2026-90050"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-17T17:16:53Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fq: clamp quantum and initial_quantum in change path\n\nThe fq change path accepts TCA_FQ_QUANTUM in [1, INT_MAX] and\nTCA_FQ_INITIAL_QUANTUM up to INT_MAX, while fq_init() already clamps to\n[1, 1\u003c\u003c20]. A user can override the init clamp via tc qdisc change,\nrestoring the small-quantum deficit spin that the init clamp prevents.\n\nNarrow iq_range.max to 1\u003c\u003c20 so TCA_FQ_INITIAL_QUANTUM is rejected at\nparse time. Clamp TCA_FQ_QUANTUM to [256, 1\u003c\u003c20] in fq_change() and\nfq_init() quantum to [256, 1\u003c\u003c20] for tiny-MTU devices.\n\nConditions to recreate the bug:\n  CONFIG_NET_SCH_FQ=y. Requires CAP_NET_ADMIN (namespace-local via\n  unshare -Urn suffices).\n\n  tc qdisc add dev dummy0 root fq\n  tc qdisc change dev dummy0 root fq quantum 1 stab data 32768 size_log 15 cell_log 0",
  "id": "GHSA-97jq-2g8v-56hq",
  "modified": "2026-09-17T18:31:48Z",
  "published": "2026-09-17T18:31:48Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90050"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/094cc07f98dfe70a34e2a1923af17fd29b8cf622"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/72e9387884554f47b03bfd40fb8b2bf52789c68d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/798283cd0fe7ba997f67e5a917f14ab40afa8d9f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a27498d34c3f429fb6db3aa609569f8154afa175"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-90050 (GCVE-0-2026-90050)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:05 – Updated: 2026-09-17 16:05

Title

net/sched: fq: clamp quantum and initial_quantum in change path

Summary

In the Linux kernel, the following vulnerability has been resolved: net/sched: fq: clamp quantum and initial_quantum in change path The fq change path accepts TCA_FQ_QUANTUM in [1, INT_MAX] and TCA_FQ_INITIAL_QUANTUM up to INT_MAX, while fq_init() already clamps to [1, 1<<20]. A user can override the init clamp via tc qdisc change, restoring the small-quantum deficit spin that the init clamp prevents. Narrow iq_range.max to 1<<20 so TCA_FQ_INITIAL_QUANTUM is rejected at parse time. Clamp TCA_FQ_QUANTUM to [256, 1<<20] in fq_change() and fq_init() quantum to [256, 1<<20] for tiny-MTU devices. Conditions to recreate the bug: CONFIG_NET_SCH_FQ=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices). tc qdisc add dev dummy0 root fq tc qdisc change dev dummy0 root fq quantum 1 stab data 32768 size_log 15 cell_log 0

Severity

No CVSS data available.

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/a27498d34c3f429fb…
https://git.kernel.org/stable/c/798283cd0fe7ba997…
https://git.kernel.org/stable/c/72e9387884554f47b…
https://git.kernel.org/stable/c/094cc07f98dfe70a3…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: d16dac3925be95ad46e986d4b139c9898b6e227f , < a27498d34c3f429fb6db3aa609569f8154afa175 (git) Affected: f6b3e3848a5fca63438984acd6d9eceac80814c1 , < 798283cd0fe7ba997f67e5a917f14ab40afa8d9f (git) Affected: e35acd56f244d94355f9ab237c2ecc8fba5e6f04 , < 72e9387884554f47b03bfd40fb8b2bf52789c68d (git) Affected: 709f34f7c28dc4dd6c40343d101850f11e172312 , < 094cc07f98dfe70a34e2a1923af17fd29b8cf622 (git)
Linux	Linux	Affected: 7.3-rc1 Unaffected: 0 , < 7.3-rc1 (semver) Unaffected: 7.3-rc3 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sched/sch_fq.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
            },
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              "status": "affected",
              "version": "f6b3e3848a5fca63438984acd6d9eceac80814c1",
              "versionType": "git"
            },
            {
              "lessThan": "72e9387884554f47b03bfd40fb8b2bf52789c68d",
              "status": "affected",
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              "versionType": "git"
            },
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              "version": "709f34f7c28dc4dd6c40343d101850f11e172312",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
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          "vendor": "Linux",
          "versions": [
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              "version": "7.3-rc1"
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              "status": "unaffected",
              "version": "0",
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              "version": "7.3-rc3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc3",
                  "versionStartIncluding": "7.3-rc1",
                  "vulnerable": true
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fq: clamp quantum and initial_quantum in change path\n\nThe fq change path accepts TCA_FQ_QUANTUM in [1, INT_MAX] and\nTCA_FQ_INITIAL_QUANTUM up to INT_MAX, while fq_init() already clamps to\n[1, 1\u003c\u003c20]. A user can override the init clamp via tc qdisc change,\nrestoring the small-quantum deficit spin that the init clamp prevents.\n\nNarrow iq_range.max to 1\u003c\u003c20 so TCA_FQ_INITIAL_QUANTUM is rejected at\nparse time. Clamp TCA_FQ_QUANTUM to [256, 1\u003c\u003c20] in fq_change() and\nfq_init() quantum to [256, 1\u003c\u003c20] for tiny-MTU devices.\n\nConditions to recreate the bug:\n  CONFIG_NET_SCH_FQ=y. Requires CAP_NET_ADMIN (namespace-local via\n  unshare -Urn suffices).\n\n  tc qdisc add dev dummy0 root fq\n  tc qdisc change dev dummy0 root fq quantum 1 stab data 32768 size_log 15 cell_log 0"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-17T16:05:36.970Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/094cc07f98dfe70a34e2a1923af17fd29b8cf622"
        }
      ],
      "title": "net/sched: fq: clamp quantum and initial_quantum in change path",
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        "engine": "bippy-1.2.0"
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90050",
    "datePublished": "2026-09-17T16:05:36.970Z",
    "dateReserved": "2026-09-11T19:38:34.783Z",
    "dateUpdated": "2026-09-17T16:05:36.970Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
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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 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-97JQ-2G8V-56HQ

CVE-2026-90050 (GCVE-0-2026-90050)

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