{"id":"CVE-2026-5818","aliases":["EUVD-2026-38638","GHSA-456r-gcjr-6rxq"],"status":"published","title":"MCU Firmware Update Authentication Bypass on Caliptra Core","description":"Incorrect check of function return value in Caliptra Core Runtime Firmware (ActivateFirmwareCmd::activate_fw modules) allows bypass of Caliptra Core's verification of the MCU FW during a hitless update.\n\nThis issue affects Core Runtime Firmware: from 2.0.0 through 2.0.1, 2.1.0.","severity":{"version":"4.0","score":7.2,"vector":"CVSS:4.0/AV:A/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:H/SC:H/SI:H/SA:H","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00245,"percentile":0.15816,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-253"],"published":"2026-06-23T23:50:06Z","modified":"2026-10-28T02:31:01Z","products":[{"vendor":"caliptra","product":"core runtime firmware"}],"references":[{"url":"https://github.com/chipsalliance/caliptra-sw/security/advisories/GHSA-456r-gcjr-6rxq","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5818.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-5818","tags":["advisory"]},{"url":"https://github.com/chipsalliance/caliptra-sw","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-5818","title":"MCU Firmware Update Authentication Bypass on Caliptra Core","description":"Incorrect check of function return value in Caliptra Core Runtime Firmware (ActivateFirmwareCmd::activate_fw modules) allows bypass of Caliptra Core's verification of the MCU FW during a hitless update.\n\nThis issue affects Core Runtime Firmware: from 2.0.0 through 2.0.1, 2.1.0.","status":"published","published":"2026-06-23T23:50:06.556Z","modified":"2026-06-24T13:04:40.166Z","cvss":[{"version":"4.0","score":7.2,"vector":"CVSS:4.0/AV:A/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:H/SC:H/SI:H/SA:H","level":"high","assessor":"cna"}],"cwes":["CWE-253"],"updated_at":"2026-11-02T13:39:27.849196Z"}],"euvd":[{"id":"EUVD-2026-38638","description":"Incorrect check of function return value in Caliptra Core Runtime Firmware (ActivateFirmwareCmd::activate_fw modules) allows bypass of Caliptra Core's verification of the MCU FW during a hitless update.\n\nThis issue affects Core Runtime Firmware: from 2.0.0 through 2.0.1, 2.1.0.","status":"published","published":"2026-06-23T23:50:06Z","modified":"2026-06-24T13:04:40Z","cvss":[{"version":"4.0","score":7.2,"vector":"CVSS:4.0/AV:A/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:H/SC:H/SI:H/SA:H","level":"high"}],"updated_at":"2026-11-02T18:20:31.123469Z"}],"nvd":[{"id":"CVE-2026-5818","description":"Incorrect check of function return value in Caliptra Core Runtime Firmware (ActivateFirmwareCmd::activate_fw modules) allows bypass of Caliptra Core's verification of the MCU FW during a hitless update.\n\nThis issue affects Core Runtime Firmware: from 2.0.0 through 2.0.1, 2.1.0.","status":"published","published":"2026-06-24T00:16:33.83Z","modified":"2026-10-25T23:10:00.167Z","cvss":[{"version":"4.0","score":7.2,"vector":"CVSS:4.0/AV:A/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"}],"cwes":["CWE-253"],"updated_at":"2026-11-02T14:12:25.288279Z"}],"osv":[{"id":"CVE-2026-5818","title":"MCU Firmware Update Authentication Bypass on Caliptra Core","description":"Incorrect check of function return value in Caliptra Core Runtime Firmware (ActivateFirmwareCmd::activate_fw modules) allows bypass of Caliptra Core's verification of the MCU FW during a hitless update.\n\nThis issue affects Core Runtime Firmware: from 2.0.0 through 2.0.1, 2.1.0.","status":"published","published":"2026-06-23T23:50:06.556Z","modified":"2026-10-28T02:31:01.141443049Z","cvss":[{"version":"4.0","score":7.2,"vector":"CVSS:4.0/AV:A/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:H/SC:H/SI:H/SA:H","level":"high"}],"cwes":["CWE-253"],"updated_at":"2026-11-02T15:45:12.016252Z"}]}}