CVE-2026-63962 (GCVE-0-2026-63962)
Vulnerability from cvelistv5
Published
2026-07-19 14:55
Modified
2026-07-20 06:41
Severity ?
Summary
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.
References
Impacted products
Vendor Product Version
Linux Linux Version: 4ab8c18d4d67321cc7b660559de17511d4fc0237
Version: 4ab8c18d4d67321cc7b660559de17511d4fc0237
Version: 4ab8c18d4d67321cc7b660559de17511d4fc0237
Version: 4ab8c18d4d67321cc7b660559de17511d4fc0237
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/usb/typec/tcpm/tcpm.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "845598b154b9a92e9d279fafafa9405c121ae805",
              "status": "affected",
              "version": "4ab8c18d4d67321cc7b660559de17511d4fc0237",
              "versionType": "git"
            },
            {
              "lessThan": "4505f33dab56c274e82f47f94bf60a8cbf8f4b42",
              "status": "affected",
              "version": "4ab8c18d4d67321cc7b660559de17511d4fc0237",
              "versionType": "git"
            },
            {
              "lessThan": "cbad85b446c06adbc5e5bed565871bb918ce9d32",
              "status": "affected",
              "version": "4ab8c18d4d67321cc7b660559de17511d4fc0237",
              "versionType": "git"
            },
            {
              "lessThan": "3389c149c68c3fea61910ad5d34f7bf3bff44e32",
              "status": "affected",
              "version": "4ab8c18d4d67321cc7b660559de17511d4fc0237",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/usb/typec/tcpm/tcpm.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.19"
            },
            {
              "lessThan": "4.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.93",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.35",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.93",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.35",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.12",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "4.19",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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-\u003ealtmodes 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-\u003epartner 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."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-20T06:41:42.766Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "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"
        }
      ],
      "title": "usb: typec: tcpm: bound altmode_desc[] per iteration in svdm_consume_modes()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63962",
    "datePublished": "2026-07-19T14:55:51.682Z",
    "dateReserved": "2026-07-19T07:54:57.024Z",
    "dateUpdated": "2026-07-20T06:41:42.766Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.