{"id":"CVE-2026-80736","state":"PUBLISHED","title":"thunderbolt: Fix bandwidth group reservation indexing","description":"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.","publishedAt":"2026-09-03T08:21:51.946Z","updatedAt":"2026-09-04T04:58:21.747Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"52a4490e89d7c4effe613d8dffd2ac0a2a786bd7","status":"affected","lessThan":"0bfb67ba366cd68d1d0ad935760577bae1d5df27","versionType":"git"},{"version":"52a4490e89d7c4effe613d8dffd2ac0a2a786bd7","status":"affected","lessThan":"9977321835c7ae71d12a43bed7baa5bd514d01c3","versionType":"git"},{"version":"52a4490e89d7c4effe613d8dffd2ac0a2a786bd7","status":"affected","lessThan":"0a8c9ed4f166216642a8c084f0de415169c88088","versionType":"git"},{"version":"52a4490e89d7c4effe613d8dffd2ac0a2a786bd7","status":"affected","lessThan":"d2ee4d47aacbd2ba456092eeec670dba35fde291","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/thunderbolt/tb.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.9","versionType":"semver"},{"version":"6.12.104","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/thunderbolt/tb.c"]}],"references":["https://git.kernel.org/stable/c/0bfb67ba366cd68d1d0ad935760577bae1d5df27","https://git.kernel.org/stable/c/9977321835c7ae71d12a43bed7baa5bd514d01c3","https://git.kernel.org/stable/c/0a8c9ed4f166216642a8c084f0de415169c88088","https://git.kernel.org/stable/c/d2ee4d47aacbd2ba456092eeec670dba35fde291"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/80xxx/CVE-2026-80736.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80736","state":"PUBLISHED","datePublished":"2026-09-03T08:21:51.946Z","dateUpdated":"2026-09-04T04:58:21.747Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-26T14:34:25.789Z"},"containers":{"cna":{"title":"thunderbolt: Fix bandwidth group reservation indexing","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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"52a4490e89d7c4effe613d8dffd2ac0a2a786bd7","status":"affected","lessThan":"0bfb67ba366cd68d1d0ad935760577bae1d5df27","versionType":"git"},{"version":"52a4490e89d7c4effe613d8dffd2ac0a2a786bd7","status":"affected","lessThan":"9977321835c7ae71d12a43bed7baa5bd514d01c3","versionType":"git"},{"version":"52a4490e89d7c4effe613d8dffd2ac0a2a786bd7","status":"affected","lessThan":"0a8c9ed4f166216642a8c084f0de415169c88088","versionType":"git"},{"version":"52a4490e89d7c4effe613d8dffd2ac0a2a786bd7","status":"affected","lessThan":"d2ee4d47aacbd2ba456092eeec670dba35fde291","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/thunderbolt/tb.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.9","versionType":"semver"},{"version":"6.12.104","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/thunderbolt/tb.c"]}],"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"}],"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."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-09-04T04:58:21.747Z"},"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"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}