CVE-2026-63962 (GCVE-0-2026-63962)

Vulnerability from cvelistv5 – Published: 2026-07-19 14:55 – Updated: 2026-07-20 06:41
VLAI
Title
usb: typec: tcpm: bound altmode_desc[] per iteration in svdm_consume_modes()
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.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 4ab8c18d4d67321cc7b660559de17511d4fc0237 , < 845598b154b9a92e9d279fafafa9405c121ae805 (git)
Affected: 4ab8c18d4d67321cc7b660559de17511d4fc0237 , < 4505f33dab56c274e82f47f94bf60a8cbf8f4b42 (git)
Affected: 4ab8c18d4d67321cc7b660559de17511d4fc0237 , < cbad85b446c06adbc5e5bed565871bb918ce9d32 (git)
Affected: 4ab8c18d4d67321cc7b660559de17511d4fc0237 , < 3389c149c68c3fea61910ad5d34f7bf3bff44e32 (git)
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Linux Linux Affected: 4.19
Unaffected: 0 , < 4.19 (semver)
Unaffected: 6.12.93 , ≤ 6.12.* (semver)
Unaffected: 6.18.35 , ≤ 6.18.* (semver)
Unaffected: 7.0.12 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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{
  "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"
            },
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              "lessThan": "4505f33dab56c274e82f47f94bf60a8cbf8f4b42",
              "status": "affected",
              "version": "4ab8c18d4d67321cc7b660559de17511d4fc0237",
              "versionType": "git"
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              "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": [
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              "status": "affected",
              "version": "4.19"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "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",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-63962",
      "date": "2026-07-21",
      "epss": "0.002",
      "percentile": "0.10013"
    },
    "microsoft_vex": {
      "current_release_date": "2026-07-21T01:02:25.000Z",
      "cve": "CVE-2026-63962",
      "id": "msrc_CVE-2026-63962",
      "initial_release_date": "2026-07-21T01:02:25.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "usb: typec: tcpm: bound altmode_desc[] per iteration in svdm_consume_modes()",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-63962.json",
      "version": "1"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-63962\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-07-19T16:17:15.163\",\"lastModified\":\"2026-07-20T07:16:41.413\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"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.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/usb/typec/tcpm/tcpm.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"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\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/usb/typec/tcpm/tcpm.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"4.19\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"4.19\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.93\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.35\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0.12\",\"lessThanOrEqual\":\"7.0.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/3389c149c68c3fea61910ad5d34f7bf3bff44e32\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/4505f33dab56c274e82f47f94bf60a8cbf8f4b42\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/845598b154b9a92e9d279fafafa9405c121ae805\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/cbad85b446c06adbc5e5bed565871bb918ce9d32\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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