{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80736","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-08-26T14:34:25.789Z","datePublished":"2026-09-03T08:21:51.946Z","dateUpdated":"2026-09-04T04:58:21.747Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-04T04:58:21.747Z"},"descriptions":[{"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's 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."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"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."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/thunderbolt/tb.c"],"versions":[{"version":"52a4490e89d7c4effe613d8dffd2ac0a2a786bd7","lessThan":"0bfb67ba366cd68d1d0ad935760577bae1d5df27","status":"affected","versionType":"git"},{"version":"52a4490e89d7c4effe613d8dffd2ac0a2a786bd7","lessThan":"9977321835c7ae71d12a43bed7baa5bd514d01c3","status":"affected","versionType":"git"},{"version":"52a4490e89d7c4effe613d8dffd2ac0a2a786bd7","lessThan":"0a8c9ed4f166216642a8c084f0de415169c88088","status":"affected","versionType":"git"},{"version":"52a4490e89d7c4effe613d8dffd2ac0a2a786bd7","lessThan":"d2ee4d47aacbd2ba456092eeec670dba35fde291","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/thunderbolt/tb.c"],"versions":[{"version":"6.9","status":"affected"},{"version":"0","lessThan":"6.9","status":"unaffected","versionType":"semver"},{"version":"6.12.104","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.45","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.1.9","lessThanOrEqual":"7.1.*","status":"unaffected","versionType":"semver"},{"version":"7.2","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.9","versionEndExcluding":"6.12.104"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.9","versionEndExcluding":"6.18.45"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.9","versionEndExcluding":"7.1.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.9","versionEndExcluding":"7.2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/0bfb67ba366cd68d1d0ad935760577bae1d5df27"},{"url":"https://git.kernel.org/stable/c/9977321835c7ae71d12a43bed7baa5bd514d01c3"},{"url":"https://git.kernel.org/stable/c/0a8c9ed4f166216642a8c084f0de415169c88088"},{"url":"https://git.kernel.org/stable/c/d2ee4d47aacbd2ba456092eeec670dba35fde291"}],"title":"thunderbolt: Fix bandwidth group reservation indexing","x_generator":{"engine":"bippy-1.2.0"}}}}