CVE-2026-80736
Received Received - Intake

Thunderbolt Bandwidth Group Reservation Indexing Fix

Publication date: 2026-09-03

Last updated on: 2026-09-03

Assigner: kernel.org

Description
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.

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Meta Information

Published
2026-09-03
Last Modified
2026-09-03
Generated
2026-09-03
AI Q&A
2026-09-03
EPSS Evaluated
N/A
NVD
CVE-2026-80736
EUVD
EUVD-2026-70340

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a Linux kernel vulnerability in the Thunderbolt subsystem. It involves incorrect array indexing in bandwidth group reservation. The issue occurs because the array used to track reserved bandwidth has MAX_GROUPS entries but valid Group IDs range from 1 to MAX_GROUPS. When Group ID MAX_GROUPS is used, it accesses memory one position past the end of the array, causing the final group's reserved bandwidth to be excluded from calculations.

Detection Guidance

This vulnerability is specific to the Linux kernel's Thunderbolt subsystem and relates to bandwidth group reservation indexing. Detection requires checking the kernel version and Thunderbolt driver implementation for the described indexing issue. No direct commands are provided in the context to detect this vulnerability.

Impact Analysis

This vulnerability could lead to incorrect bandwidth allocation for Thunderbolt devices. It may cause performance issues or unexpected behavior when multiple high-bandwidth devices are connected simultaneously. The impact is limited to Thunderbolt functionality and does not affect other system components.

Mitigation Strategies

Apply the Linux kernel patch that resolves the Thunderbolt bandwidth group reservation indexing issue. Update to a kernel version that includes the fix for this specific vulnerability. Monitor vendor advisories for distribution-specific updates.

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