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GHSA-G6C9-VF65-GGGG

Vulnerability from github – Published: 2026-09-03 15:32 – Updated: 2026-09-04 06:31

Details

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

thunderbolt: Fix bandwidth group reservation indexing

Valid bandwidth group IDs range from 1 through MAX_GROUPS, while Group ID 0 is reserved. tb_consumed_dp_bandwidth() uses the Group ID directly to index its local group_reserved[] array.

The array currently has MAX_GROUPS entries, so its valid indices are 0 through MAX_GROUPS - 1. Group ID MAX_GROUPS therefore accesses one element past the end, and the final group's reserved bandwidth is not included when the array is summed.

Give group_reserved[] MAX_GROUPS + 1 entries so direct Group ID indexing covers the reserved ID 0 and valid IDs 1 through MAX_GROUPS.

Severity

7.8 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-80736"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-03T13:06:12Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nthunderbolt: Fix bandwidth group reservation indexing\n\nValid bandwidth group IDs range from 1 through MAX_GROUPS, while Group\nID 0 is reserved. tb_consumed_dp_bandwidth() uses the Group ID directly\nto index its local group_reserved[] array.\n\nThe array currently has MAX_GROUPS entries, so its valid indices are 0\nthrough MAX_GROUPS - 1. Group ID MAX_GROUPS therefore accesses one\nelement past the end, and the final group\u0027s reserved bandwidth is not\nincluded when the array is summed.\n\nGive group_reserved[] MAX_GROUPS + 1 entries so direct Group ID\nindexing covers the reserved ID 0 and valid IDs 1 through MAX_GROUPS.",
  "id": "GHSA-g6c9-vf65-gggg",
  "modified": "2026-09-04T06:31:20Z",
  "published": "2026-09-03T15:32:15Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80736"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0a8c9ed4f166216642a8c084f0de415169c88088"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0bfb67ba366cd68d1d0ad935760577bae1d5df27"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9977321835c7ae71d12a43bed7baa5bd514d01c3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d2ee4d47aacbd2ba456092eeec670dba35fde291"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-80736 (GCVE-0-2026-80736)

Vulnerability from cvelistv5 – Published: 2026-09-03 08:21 – Updated: 2026-09-04 04:58

Title

thunderbolt: Fix bandwidth group reservation indexing

Summary

In the Linux kernel, the following vulnerability has been resolved: thunderbolt: Fix bandwidth group reservation indexing Valid bandwidth group IDs range from 1 through MAX_GROUPS, while Group ID 0 is reserved. tb_consumed_dp_bandwidth() uses the Group ID directly to index its local group_reserved[] array. The array currently has MAX_GROUPS entries, so its valid indices are 0 through MAX_GROUPS - 1. Group ID MAX_GROUPS therefore accesses one element past the end, and the final group's reserved bandwidth is not included when the array is summed. Give group_reserved[] MAX_GROUPS + 1 entries so direct Group ID indexing covers the reserved ID 0 and valid IDs 1 through MAX_GROUPS.

Severity

7.8 (High)


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

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/0bfb67ba366cd68d1…
https://git.kernel.org/stable/c/9977321835c7ae71d…
https://git.kernel.org/stable/c/0a8c9ed4f16621664…
https://git.kernel.org/stable/c/d2ee4d47aacbd2ba4…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 52a4490e89d7c4effe613d8dffd2ac0a2a786bd7 , < 0bfb67ba366cd68d1d0ad935760577bae1d5df27 (git) Affected: 52a4490e89d7c4effe613d8dffd2ac0a2a786bd7 , < 9977321835c7ae71d12a43bed7baa5bd514d01c3 (git) Affected: 52a4490e89d7c4effe613d8dffd2ac0a2a786bd7 , < 0a8c9ed4f166216642a8c084f0de415169c88088 (git) Affected: 52a4490e89d7c4effe613d8dffd2ac0a2a786bd7 , < d2ee4d47aacbd2ba456092eeec670dba35fde291 (git)
Linux	Linux	Affected: 6.9 Unaffected: 0 , < 6.9 (semver) Unaffected: 6.12.104 , ≤ 6.12.* (semver) Unaffected: 6.18.45 , ≤ 6.18.* (semver) Unaffected: 7.1.9 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/thunderbolt/tb.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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              "status": "affected",
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              "versionType": "git"
            },
            {
              "lessThan": "9977321835c7ae71d12a43bed7baa5bd514d01c3",
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.9"
            },
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              "lessThan": "6.9",
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              "version": "0",
              "versionType": "semver"
            },
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              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.45",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "7.1.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
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          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.104",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nthunderbolt: Fix bandwidth group reservation indexing\n\nValid bandwidth group IDs range from 1 through MAX_GROUPS, while Group\nID 0 is reserved. tb_consumed_dp_bandwidth() uses the Group ID directly\nto index its local group_reserved[] array.\n\nThe array currently has MAX_GROUPS entries, so its valid indices are 0\nthrough MAX_GROUPS - 1. Group ID MAX_GROUPS therefore accesses one\nelement past the end, and the final group\u0027s reserved bandwidth is not\nincluded when the array is summed.\n\nGive group_reserved[] MAX_GROUPS + 1 entries so direct Group ID\nindexing covers the reserved ID 0 and valid IDs 1 through MAX_GROUPS."
        }
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The flaw is reached through the local Thunderbolt connection manager control channel (TB_CFG_ERROR_DP_BW notifications into tb_handle_dp_bandwidth_request/tb_alloc_dp_bandwidth), not over IP; on systems with authorized TB docks/workstations, DP bandwidth recalculation can be driven without new network access.\nAC:L - After an authorized topology uses bandwidth group 7 with reserved DP bandwidth, the out-of-bounds write at group_reserved[7] is deterministic whenever tb_consumed_dp_bandwidth() runs; an attacker can induce the needed bandwidth reductions/mode changes rather than depending on uncontrollable timing.\nPR:L - The vulnerable path performs no credential checks; once Thunderbolt devices are authorized (common with security level none or boot ACL), an unprivileged local user can trigger DP bandwidth allocation events via display/mode changes that cause DPTX bandwidth notifications.\nUI:N - No victim interaction is required beyond normal authorized Thunderbolt/DisplayPort operation; a local attacker can directly cause the bandwidth-change notifications that reach tb_consumed_dp_bandwidth() without convincing another user to perform a separate action.\nS:U - Impact is kernel stack corruption during Thunderbolt bandwidth accounting in the host kernel; it does not cross a VM/host, IOMMU/DMA, or sandbox security boundary and stays within the same kernel security authority.\nC:H - Indexing group_reserved[] with group ID 7 writes one 32-bit word past a seven-element stack array, corrupting adjacent stack data with attacker-influenced reserved-bandwidth values and enabling kernel memory disclosure primitives.\nI:H - This is a kernel stack out-of-bounds write with partially attacker-controlled values (reserved Mb/s), which can corrupt pointers/control data on the stack and be leveraged for arbitrary kernel memory modification or privilege escalation.\nA:H - Corrupting kernel stack variables in tb_consumed_dp_bandwidth() can cause immediate kernel oops/panic or hang during bandwidth accounting, and unstable stack corruption commonly produces severe system unavailability."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-04T04:58:21.747Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/0a8c9ed4f166216642a8c084f0de415169c88088"
        },
        {
          "url": "https://git.kernel.org/stable/c/d2ee4d47aacbd2ba456092eeec670dba35fde291"
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      ],
      "title": "thunderbolt: Fix bandwidth group reservation indexing",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80736",
    "datePublished": "2026-09-03T08:21:51.946Z",
    "dateReserved": "2026-08-26T14:34:25.789Z",
    "dateUpdated": "2026-09-04T04:58:21.747Z",
    "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.

Detection rules are retrieved from Rulezet.

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-G6C9-VF65-GGGG

CVE-2026-80736 (GCVE-0-2026-80736)

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Sightings

Nomenclature