{"id":"CVE-2026-63962","state":"PUBLISHED","title":"usb: typec: tcpm: bound altmode_desc[] per iteration in svdm_consume_modes()","description":"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.","publishedAt":"2026-07-19T14:55:51.682Z","updatedAt":"2026-10-30T12:27:23.506Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4ab8c18d4d67321cc7b660559de17511d4fc0237","status":"affected","lessThan":"f6694bac643c7ae25c0634b63e67d573ed31e5b7","versionType":"git"},{"version":"4ab8c18d4d67321cc7b660559de17511d4fc0237","status":"affected","lessThan":"816c6251409db28f1b875988fcbd2ff1764a81f0","versionType":"git"},{"version":"4ab8c18d4d67321cc7b660559de17511d4fc0237","status":"affected","lessThan":"845598b154b9a92e9d279fafafa9405c121ae805","versionType":"git"},{"version":"4ab8c18d4d67321cc7b660559de17511d4fc0237","status":"affected","lessThan":"4505f33dab56c274e82f47f94bf60a8cbf8f4b42","versionType":"git"},{"version":"4ab8c18d4d67321cc7b660559de17511d4fc0237","status":"affected","lessThan":"cbad85b446c06adbc5e5bed565871bb918ce9d32","versionType":"git"},{"version":"4ab8c18d4d67321cc7b660559de17511d4fc0237","status":"affected","lessThan":"3389c149c68c3fea61910ad5d34f7bf3bff44e32","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/typec/tcpm/tcpm.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.19","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.93","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.35","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.12","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/typec/tcpm/tcpm.c"]}],"references":["https://git.kernel.org/stable/c/f6694bac643c7ae25c0634b63e67d573ed31e5b7","https://git.kernel.org/stable/c/816c6251409db28f1b875988fcbd2ff1764a81f0","https://git.kernel.org/stable/c/845598b154b9a92e9d279fafafa9405c121ae805","https://git.kernel.org/stable/c/4505f33dab56c274e82f47f94bf60a8cbf8f4b42","https://git.kernel.org/stable/c/cbad85b446c06adbc5e5bed565871bb918ce9d32","https://git.kernel.org/stable/c/3389c149c68c3fea61910ad5d34f7bf3bff44e32"],"weaknesses":[],"ingestedAt":"2026-10-30T12:46:06.359Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63962.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63962","state":"PUBLISHED","datePublished":"2026-07-19T14:55:51.682Z","dateUpdated":"2026-10-30T12:27:23.506Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.024Z"},"containers":{"cna":{"title":"usb: typec: tcpm: bound altmode_desc[] per iteration in svdm_consume_modes()","descriptions":[{"lang":"en","value":"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":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4ab8c18d4d67321cc7b660559de17511d4fc0237","status":"affected","lessThan":"f6694bac643c7ae25c0634b63e67d573ed31e5b7","versionType":"git"},{"version":"4ab8c18d4d67321cc7b660559de17511d4fc0237","status":"affected","lessThan":"816c6251409db28f1b875988fcbd2ff1764a81f0","versionType":"git"},{"version":"4ab8c18d4d67321cc7b660559de17511d4fc0237","status":"affected","lessThan":"845598b154b9a92e9d279fafafa9405c121ae805","versionType":"git"},{"version":"4ab8c18d4d67321cc7b660559de17511d4fc0237","status":"affected","lessThan":"4505f33dab56c274e82f47f94bf60a8cbf8f4b42","versionType":"git"},{"version":"4ab8c18d4d67321cc7b660559de17511d4fc0237","status":"affected","lessThan":"cbad85b446c06adbc5e5bed565871bb918ce9d32","versionType":"git"},{"version":"4ab8c18d4d67321cc7b660559de17511d4fc0237","status":"affected","lessThan":"3389c149c68c3fea61910ad5d34f7bf3bff44e32","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/typec/tcpm/tcpm.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.19","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.93","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.35","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.12","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/typec/tcpm/tcpm.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/f6694bac643c7ae25c0634b63e67d573ed31e5b7"},{"url":"https://git.kernel.org/stable/c/816c6251409db28f1b875988fcbd2ff1764a81f0"},{"url":"https://git.kernel.org/stable/c/845598b154b9a92e9d279fafafa9405c121ae805"},{"url":"https://git.kernel.org/stable/c/4505f33dab56c274e82f47f94bf60a8cbf8f4b42"},{"url":"https://git.kernel.org/stable/c/cbad85b446c06adbc5e5bed565871bb918ce9d32"},{"url":"https://git.kernel.org/stable/c/3389c149c68c3fea61910ad5d34f7bf3bff44e32"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:27:23.506Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"6.12.93"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"6.18.35"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"7.0.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}