{"schema_version":"1.9.0","id":"CVE-2026-63962","published":"2026-07-19T14:55:51.682Z","modified":"2026-08-31T18:26:04.033927490Z","related":["SUSE-SU-2026:23066-1","SUSE-SU-2026:23068-1","SUSE-SU-2026:23193-1","SUSE-SU-2026:23194-1","SUSE-SU-2026:23221-1","SUSE-SU-2026:23231-1","SUSE-SU-2026:23237-1","SUSE-SU-2026:23241-1","SUSE-SU-2026:23244-1","SUSE-SU-2026:3790-1","SUSE-SU-2026:3810-1","openSUSE-SU-2026:21555-1"],"summary":"usb: typec: tcpm: bound altmode_desc[] per iteration in svdm_consume_modes()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nusb: typec: tcpm: bound altmode_desc[] per iteration in svdm_consume_modes()\n\nsvdm_consume_modes() checks pmdata->altmodes against the array size once\nbefore the loop over the count, but forgot to check the bound at every\npoint in the loop.\n\nIn the well-behaved SVDM discovery flow this is harmless because each of\nat most SVID_DISCOVERY_MAX SVIDs contributes at most MODE_DISCOVERY_MAX\nmodes, exactly filling altmode_desc[ALTMODE_DISCOVERY_MAX].  But the\nCMDT_RSP_ACK handler in tcpm_pd_svdm() does not correlate an incoming\nACK with any request the port actually sent.  Once port->partner is set,\nan unsolicited Discover Modes ACK is consumed unconditionally.  A broken\nor malicious port partner can therefore drive altmodes to\nALTMODE_DISCOVERY_MAX - 1 via the normal flow, and then send one extra\nDiscover Modes ACK with seven VDOs.  Because the pre-loop check passes,\nthe loop could then writes up to five entries past altmode_desc[].  For\nmode_data_prime the next field in struct tcpm_port is the\npartner_altmode[] pointer array, which then receives partner-chosen\nSVID/VDO bytes.\n\nMove the bound check inside the loop so the array can never be indexed\npast ALTMODE_DISCOVERY_MAX regardless of how many VDOs the partner\nsupplies or how the function was reached.","affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"4ab8c18d4d67321cc7b660559de17511d4fc0237"},{"fixed":"845598b154b9a92e9d279fafafa9405c121ae805"},{"fixed":"4505f33dab56c274e82f47f94bf60a8cbf8f4b42"},{"fixed":"cbad85b446c06adbc5e5bed565871bb918ce9d32"},{"fixed":"3389c149c68c3fea61910ad5d34f7bf3bff44e32"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63962.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.19.0"},{"fixed":"6.12.93"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.35"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.12"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63962.json"}}],"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/3389c149c68c3fea61910ad5d34f7bf3bff44e32"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4505f33dab56c274e82f47f94bf60a8cbf8f4b42"},{"type":"WEB","url":"https://git.kernel.org/stable/c/845598b154b9a92e9d279fafafa9405c121ae805"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cbad85b446c06adbc5e5bed565871bb918ce9d32"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63962.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63962"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63962.json"}}