usb: typec: tcpm: bound altmode_desc[] per iteration in svdm_consume_modes()
Summary
| CVE | CVE-2026-63962 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-19 16:17:15 UTC |
| Updated | 2026-07-20 07:16:41 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: usb: typec: tcpm: bound altmode_desc[] per iteration in svdm_consume_modes() svdm_consume_modes() checks pmdata->altmodes against the array size once before the loop over the count, but forgot to check the bound at every point in the loop. In the well-behaved SVDM discovery flow this is harmless because each of at most SVID_DISCOVERY_MAX SVIDs contributes at most MODE_DISCOVERY_MAX modes, exactly filling altmode_desc[ALTMODE_DISCOVERY_MAX]. But the CMDT_RSP_ACK handler in tcpm_pd_svdm() does not correlate an incoming ACK with any request the port actually sent. Once port->partner is set, an unsolicited Discover Modes ACK is consumed unconditionally. A broken or malicious port partner can therefore drive altmodes to ALTMODE_DISCOVERY_MAX - 1 via the normal flow, and then send one extra Discover Modes ACK with seven VDOs. Because the pre-loop check passes, the loop could then writes up to five entries past altmode_desc[]. For mode_data_prime the next field in struct tcpm_port is the partner_altmode[] pointer array, which then receives partner-chosen SVID/VDO bytes. Move the bound check inside the loop so the array can never be indexed past ALTMODE_DISCOVERY_MAX regardless of how many VDOs the partner supplies or how the function was reached. |
Risk And Classification
EPSS: 0.002000000 probability, percentile 0.100200000 (date 2026-07-20)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 4ab8c18d4d67321cc7b660559de17511d4fc0237 845598b154b9a92e9d279fafafa9405c121ae805 git | Not specified |
| CNA | Linux | Linux | affected 4ab8c18d4d67321cc7b660559de17511d4fc0237 4505f33dab56c274e82f47f94bf60a8cbf8f4b42 git | Not specified |
| CNA | Linux | Linux | affected 4ab8c18d4d67321cc7b660559de17511d4fc0237 cbad85b446c06adbc5e5bed565871bb918ce9d32 git | Not specified |
| CNA | Linux | Linux | affected 4ab8c18d4d67321cc7b660559de17511d4fc0237 3389c149c68c3fea61910ad5d34f7bf3bff44e32 git | Not specified |
| CNA | Linux | Linux | affected 4.19 | Not specified |
| CNA | Linux | Linux | unaffected 4.19 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.93 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.35 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.0.12 7.0.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/3389c149c68c3fea61910ad5d34f7bf3bff44e32 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/4505f33dab56c274e82f47f94bf60a8cbf8f4b42 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/845598b154b9a92e9d279fafafa9405c121ae805 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/cbad85b446c06adbc5e5bed565871bb918ce9d32 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.