{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99216","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-25T10:25:14.401Z","datePublished":"2026-10-28T10:36:09.383Z","dateUpdated":"2026-10-31T12:45:15.499Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-10-31T12:45:15.499Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nDrivers: hv: Don't reset VMBus connection state on error/exit paths\n\nIn two places, current code forces vmbus_connection.conn_state to\nDISCONNECTED prior to calling vmbus_disconnect(). But vmbus_disconnect()\ncalls vmbus_initiate_unload(), which unloads the VMBus connection\nonly if the conn_state is CONNECTED. Consequently, the connection\nremains and the Hyper-V host might continue to send messages or post\nVMBus interrupts.\n\nThe problem was introduced in commit 74347a99e73ae (\"x86/Hyper-V:\nUnload vmbus channel in hv panic callback\"), in that\nvmbus_initiate_unload() started checking the current connection\nstate before doing the unload. This commit removed some occurrences\nwhere conn_state was forced to DISCONNECTED, but these two remained,\napparently due to an oversight at the time.\n\nFix this by not forcing conn_state to DISCONNECTED during VMBus exit,\nor if a failure occurs when establishing the connection in the first\nplace. Whatever value conn_state has at the time is then read by\nvmbus_initiate_unload() to determine if there is a connection to\nbe unloaded."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":8.4,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The attacker-controlled CHANNELMSG_VERSION_RESPONSE reaches vmbus_connect() through sysvec_hyperv_callback, vmbus_isr(), vmbus_on_msg_dpc(), and vmbus_onversion_response(); this is local Hyper-V IPC, not a network or physical protocol.\nAC:L - A backend can reject versions through 5.2, accept 5.1 in an isolation guest, then post rescind messages while the patched vmbus_connect() cleanup destroys its queues. The same backend controls both the state setup and racing messages.\nPR:N - vmbus_onversion_response() accepts the Hyper-V parent's VERSION_RESPONSE from the SynIC message page without guest credentials, capabilities, or authentication; the backend needs no privilege inside the guest.\nUI:N - hv_acpi_init() automatically calls vmbus_bus_init(), vmbus_alloc_synic_and_connect(), and vmbus_connect() during driver initialization; the backend supplies the responses without any victim action.\nS:U - The stale rescind_work_queue/work_queue accesses and resulting corruption occur within the same guest kernel that contains the vulnerable VMBus driver; no guest-to-host escape or IOMMU boundary bypass is produced.\nC:H - Without CHANNELMSG_UNLOAD, __vmbus_on_msg_dpc() can queue a rescind through a workqueue already RCU-freed by vmbus_disconnect(); this kernel heap use-after-free permits object reuse and guest-kernel memory disclosure.\nI:H - queue_work() dereferences the freed workqueue's cpu_pwq and updates pool counters and work-list state, so reuse of that storage can turn continued host messages into kernel heap writes and control-flow corruption.\nA:H - Continued rescind or offer messages can make __queue_work() access a destroyed or freed workqueue before hv_synic_cleanup() disables the SynIC, causing a warning, invalid-pointer fault, kernel oops, or panic."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/hv/connection.c","drivers/hv/vmbus_drv.c"],"versions":[{"version":"74347a99e73ae00b8385f1209aaea193c670f901","lessThan":"2939215d57bc8e4189290544fca78f3809ac3ef8","status":"affected","versionType":"git"},{"version":"74347a99e73ae00b8385f1209aaea193c670f901","lessThan":"a0ae955ba9a5067a157ebb8defb4a0a9cb1fc304","status":"affected","versionType":"git"},{"version":"74347a99e73ae00b8385f1209aaea193c670f901","lessThan":"deef3ab5129ae4c45662c957cdab3739eb047fb1","status":"affected","versionType":"git"},{"version":"74347a99e73ae00b8385f1209aaea193c670f901","lessThan":"2e5ffbf1e41abbf6e02ce28115107938f55ff646","status":"affected","versionType":"git"},{"version":"74347a99e73ae00b8385f1209aaea193c670f901","lessThan":"2732210132f92aca0622b5134027990a809279d5","status":"affected","versionType":"git"},{"version":"74347a99e73ae00b8385f1209aaea193c670f901","lessThan":"f47ce27af80b87cc684d5c12b65506af498ac7e5","status":"affected","versionType":"git"},{"version":"74347a99e73ae00b8385f1209aaea193c670f901","lessThan":"3195546a377c2d8d176d837e8baad5ce15d11195","status":"affected","versionType":"git"},{"version":"74347a99e73ae00b8385f1209aaea193c670f901","lessThan":"ec31dc39e835ccde0930daccece8c492d28282fc","status":"affected","versionType":"git"},{"version":"5e059fc0f054309036d3f612bc8b0a502ca58545","status":"affected","versionType":"git"},{"version":"9f38f7b46de0747c1909e8c557aa21715dce20c5","status":"affected","versionType":"git"},{"version":"caeeb3787167c884b955404a7e669fd77f267e44","status":"affected","versionType":"git"},{"version":"4.19.118","lessThan":"4.20","status":"affected","versionType":"semver"},{"version":"5.4.35","lessThan":"5.5","status":"affected","versionType":"semver"},{"version":"5.6.7","lessThan":"5.7","status":"affected","versionType":"semver"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/hv/connection.c","drivers/hv/vmbus_drv.c"],"versions":[{"version":"5.7","status":"affected"},{"version":"0","lessThan":"5.7","status":"unaffected","versionType":"semver"},{"version":"5.10.273","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.224","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.191","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.161","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.115","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.59","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.13","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","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":"5.7","versionEndExcluding":"5.10.273"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"5.15.224"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.6.161"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.12.115"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.18.59"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"7.2.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"7.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19.118"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4.35"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.6.7"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/2939215d57bc8e4189290544fca78f3809ac3ef8"},{"url":"https://git.kernel.org/stable/c/a0ae955ba9a5067a157ebb8defb4a0a9cb1fc304"},{"url":"https://git.kernel.org/stable/c/deef3ab5129ae4c45662c957cdab3739eb047fb1"},{"url":"https://git.kernel.org/stable/c/2e5ffbf1e41abbf6e02ce28115107938f55ff646"},{"url":"https://git.kernel.org/stable/c/2732210132f92aca0622b5134027990a809279d5"},{"url":"https://git.kernel.org/stable/c/f47ce27af80b87cc684d5c12b65506af498ac7e5"},{"url":"https://git.kernel.org/stable/c/3195546a377c2d8d176d837e8baad5ce15d11195"},{"url":"https://git.kernel.org/stable/c/ec31dc39e835ccde0930daccece8c492d28282fc"}],"title":"Drivers: hv: Don't reset VMBus connection state on error/exit paths","x_generator":{"engine":"bippy-1.2.0"}}}}