FKIE_CVE-2026-127915

Vulnerability from fkie_nvd - Published: 2026-11-13 02:18 - Updated: 2026-11-13 02:18
Severity
2.0 (Low) - CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Summary
The MCUboot TLV iterator bootutil_tlv_iter_next() in boot/bootutil/src/tlv.c walks image trailer TLVs with a single loop guard (it->tlv_off < it->tlv_end) and advances by sizeof(struct image_tlv) + tlv.it_len using the attacker-controlled it_len field, without validating that the entry's header or payload stays within it->tlv_end. As a result the 4-byte header read can extend up to 3 bytes past the declared TLV area, and the returned (off, len) can describe a payload that runs past it. The path is pre-authentication: TLVs are parsed during bootutil_img_validate() before the signature is verified, and a crafted image can be presented through DFU / serial-recovery / OTA. However the impact is contained by surrounding guards: bootutil_img_validate() first rejects a TLV area larger than bootutil_max_image_size(), the default LOAD_IMAGE_DATA sink is flash_area_read() which bounds-checks against the flash partition and fails an out-of-partition read, and every payload consumer (EXPECTED_HASH_TLV, EXPECTED_KEY_TLV, EXPECTED_SIG_TLV, IMAGE_TLV_SEC_CNT) clamps len against a fixed buffer before copying. The residual effect in a default flash build is therefore an out-of-region read confined to the attacker's own slot partition whose result is never observable, yielding at worst a clean validation failure rather than memory corruption or information disclosure. A genuine (though still bounded) out-of-bounds read remains under the non-default MCUBOOT_RAM_LOAD configuration, where LOAD_IMAGE_DATA is an unchecked memcpy. The fix is to validate each entry's header and payload against it->tlv_end inside the iterator.
References
vulnerabilities@zephyrproject.orghttps://github.com/mcu-tools/mcuboot/commit/90f4e7c3ebe4cf9a5eb7d981220388ffdefd6d19
vulnerabilities@zephyrproject.orghttps://github.com/mcu-tools/mcuboot/security/advisories/GHSA-4fp3-3qw2-25jv
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://github.com/mcu-tools/mcuboot",
          "defaultStatus": "unaffected",
          "packageName": "mcuboot",
          "product": "mcuboot",
          "programFiles": [
            "boot/bootutil/src/image_validate.c",
            "boot/bootutil/src/tlv.c"
          ],
          "programRoutines": [
            {
              "name": "bootutil_img_validate"
            },
            {
              "name": "bootutil_tlv_iter_next"
            }
          ],
          "vendor": "mcu-tools",
          "versions": [
            {
              "lessThan": "2.5.0",
              "status": "affected",
              "version": "0.9.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "vulnerabilities@zephyrproject.org"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "The MCUboot TLV iterator bootutil_tlv_iter_next() in boot/bootutil/src/tlv.c walks image trailer TLVs with a single loop guard (it-\u003etlv_off \u003c it-\u003etlv_end) and advances by sizeof(struct image_tlv) + tlv.it_len using the attacker-controlled it_len field, without validating that the entry\u0027s header or payload stays within it-\u003etlv_end. As a result the 4-byte header read can extend up to 3 bytes past the declared TLV area, and the returned (off, len) can describe a payload that runs past it.\n\nThe path is pre-authentication: TLVs are parsed during bootutil_img_validate() before the signature is verified, and a crafted image can be presented through DFU / serial-recovery / OTA. However the impact is contained by surrounding guards: bootutil_img_validate() first rejects a TLV area larger than bootutil_max_image_size(), the default LOAD_IMAGE_DATA sink is flash_area_read() which bounds-checks against the flash partition and fails an out-of-partition read, and every payload consumer (EXPECTED_HASH_TLV, EXPECTED_KEY_TLV, EXPECTED_SIG_TLV, IMAGE_TLV_SEC_CNT) clamps len against a fixed buffer before copying.\n\nThe residual effect in a default flash build is therefore an out-of-region read confined to the attacker\u0027s own slot partition whose result is never observable, yielding at worst a clean validation failure rather than memory corruption or information disclosure. A genuine (though still bounded) out-of-bounds read remains under the non-default MCUBOOT_RAM_LOAD configuration, where LOAD_IMAGE_DATA is an unchecked memcpy. The fix is to validate each entry\u0027s header and payload against it-\u003etlv_end inside the iterator."
    }
  ],
  "id": "CVE-2026-127915",
  "lastModified": "2026-11-13T02:18:55.863",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "PHYSICAL",
          "availabilityImpact": "LOW",
          "baseScore": 2.0,
          "baseSeverity": "LOW",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 0.5,
        "impactScore": 1.4,
        "source": "vulnerabilities@zephyrproject.org",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-11-13T02:18:55.863",
  "references": [
    {
      "source": "vulnerabilities@zephyrproject.org",
      "url": "https://github.com/mcu-tools/mcuboot/commit/90f4e7c3ebe4cf9a5eb7d981220388ffdefd6d19"
    },
    {
      "source": "vulnerabilities@zephyrproject.org",
      "url": "https://github.com/mcu-tools/mcuboot/security/advisories/GHSA-4fp3-3qw2-25jv"
    }
  ],
  "sourceIdentifier": "vulnerabilities@zephyrproject.org",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-125"
        }
      ],
      "source": "vulnerabilities@zephyrproject.org",
      "type": "Secondary"
    }
  ]
}



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