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usb: typec: tcpm: bound altmode_desc[] per iteration in svdm_consume_modes()

Type: advisorySource: Official CVE List1 source record

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.

Announced Source revision 1
Original source ↗

CVE-2026-63962

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-63962

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4ab8c18d4d67321cc7b660559de17511d4fc0237",
        "lessThan": "816c6251409db28f1b875988fcbd2ff1764a81f0",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4ab8c18d4d67321cc7b660559de17511d4fc0237",
        "lessThan": "845598b154b9a92e9d279fafafa9405c121ae805",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4ab8c18d4d67321cc7b660559de17511d4fc0237",
        "lessThan": "4505f33dab56c274e82f47f94bf60a8cbf8f4b42",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4ab8c18d4d67321cc7b660559de17511d4fc0237",
        "lessThan": "cbad85b446c06adbc5e5bed565871bb918ce9d32",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4ab8c18d4d67321cc7b660559de17511d4fc0237",
        "lessThan": "3389c149c68c3fea61910ad5d34f7bf3bff44e32",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "drivers/usb/typec/tcpm/tcpm.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.19"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.19",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.93",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.35",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.0.12",
        "versionType": "semver",
        "lessThanOrEqual": "7.0.*"
      },
      {
        "status": "unaffected",
        "version": "7.1",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "drivers/usb/typec/tcpm/tcpm.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-63962

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#46405 · Revision 1
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