{"api_version":"1","generated_at":"2026-11-13T05:20:30+00:00","cve":"CVE-2026-127915","urls":{"html":"https://cve.report/CVE-2026-127915","api":"https://cve.report/api/cve/CVE-2026-127915.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-127915","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-127915"},"summary":{"title":"TLV iterator does not bound each entry against the declared TLV area in MCUboot bootutil","description":"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.\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'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.","state":"PUBLISHED","assigner":"zephyr","published_at":"2026-11-13 02:18:55","updated_at":"2026-11-13 02:18:55"},"problem_types":["CWE-125","CWE-125 bounds"],"metrics":[{"version":"3.1","source":"vulnerabilities@zephyrproject.org","type":"Secondary","score":"2","severity":"LOW","vector":"CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","baseScore":2,"baseSeverity":"LOW","attackVector":"PHYSICAL","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"LOW"}},{"version":"3.1","source":"CNA","type":"CVSS","score":"2","severity":"LOW","vector":"CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","data":{"baseScore":2,"baseSeverity":"LOW","vectorString":"CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"}}],"references":[{"url":"https://github.com/mcu-tools/mcuboot/commit/90f4e7c3ebe4cf9a5eb7d981220388ffdefd6d19","name":"https://github.com/mcu-tools/mcuboot/commit/90f4e7c3ebe4cf9a5eb7d981220388ffdefd6d19","refsource":"vulnerabilities@zephyrproject.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/mcu-tools/mcuboot/security/advisories/GHSA-4fp3-3qw2-25jv","name":"https://github.com/mcu-tools/mcuboot/security/advisories/GHSA-4fp3-3qw2-25jv","refsource":"vulnerabilities@zephyrproject.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-127915","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-127915","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"mcu-tools","product":"mcuboot","version":"affected 0.9.0 2.5.0 semver","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"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"}]}],"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->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.\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'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."}],"metrics":[{"cvssV3_1":{"baseScore":2,"baseSeverity":"LOW","vectorString":"CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"},"format":"CVSS"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-125","description":"bounds","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-11-13T00:23:07.449Z","orgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","shortName":"zephyr"},"references":[{"name":"Fix commit","tags":["patch"],"url":"https://github.com/mcu-tools/mcuboot/commit/90f4e7c3ebe4cf9a5eb7d981220388ffdefd6d19"},{"name":"GHSA-4fp3-3qw2-25jv","url":"https://github.com/mcu-tools/mcuboot/security/advisories/GHSA-4fp3-3qw2-25jv"}],"title":"TLV iterator does not bound each entry against the declared TLV area in MCUboot bootutil","x_generator":{"engine":"cvelib 1.8.0"}}},"cveMetadata":{"assignerOrgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","assignerShortName":"zephyr","cveId":"CVE-2026-127915","datePublished":"2026-11-13T00:23:07.449Z","dateReserved":"2026-11-12T18:50:53.746Z","dateUpdated":"2026-11-13T00:23:07.449Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-11-13 02:18:55","lastModifiedDate":"2026-11-13 02:18:55","problem_types":["CWE-125","CWE-125 bounds"],"metrics":{"cvssMetricV31":[{"source":"vulnerabilities@zephyrproject.org","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","baseScore":2,"baseSeverity":"LOW","attackVector":"PHYSICAL","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"LOW"},"exploitabilityScore":0.5,"impactScore":1.4}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"127915","Ordinal":"1","Title":"TLV iterator does not bound each entry against the declared TLV ","CVE":"CVE-2026-127915","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"127915","Ordinal":"1","NoteData":"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.\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'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.","Type":"Description","Title":"TLV iterator does not bound each entry against the declared TLV "}]}}}