{"id":"CVE-2026-11835","aliases":["EUVD-2026-52549","GHSA-49mm-5gq5-v97f"],"status":"published","title":"Caliptra Update-Reset Secure-Boot Bypass via Attacker-Chosen AXI Staging Address (TOCTOU)","description":"Time-of-check time-of-use (TOCTOU) vulnerability combined with missing input validation in Caliptra Core ROM (UpdateResetFlow::run()) in subsystem mode allows a compromised local attacker to silently bypass secure boot by supplying an AXI staging address that is not validated against the strap-configured SS_EXTERNAL_STAGING_AREA_BASE_ADDR, enabling firmware to be modified between verification and loading into ICCM. Attestation continues to report the originally verified image digest, masking the compromise. Exploitation requires a compromised MCU firmware with AXI manager access to unprotected SRAM reachable by Caliptra.\n\nThis issue affects Core ROM: 2.1.0 through 2.1.1.","severity":{"version":"4.0","score":5.6,"vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00108,"percentile":0.01198,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-20","CWE-367"],"published":"2026-08-04T00:03:23Z","modified":"2026-10-28T02:30:51Z","products":[{"vendor":"caliptra","product":"core rom"}],"references":[{"url":"https://github.com/chipsalliance/caliptra-sw/security/advisories/GHSA-49mm-5gq5-v97f","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/11xxx/CVE-2026-11835.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-11835","tags":["advisory"]},{"url":"https://github.com/chipsalliance/caliptra-sw","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-11835","title":"Caliptra Update-Reset Secure-Boot Bypass via Attacker-Chosen AXI Staging Address (TOCTOU)","description":"Time-of-check time-of-use (TOCTOU) vulnerability combined with missing input validation in Caliptra Core ROM (UpdateResetFlow::run()) in subsystem mode allows a compromised local attacker to silently bypass secure boot by supplying an AXI staging address that is not validated against the strap-configured SS_EXTERNAL_STAGING_AREA_BASE_ADDR, enabling firmware to be modified between verification and loading into ICCM. Attestation continues to report the originally verified image digest, masking the compromise. Exploitation requires a compromised MCU firmware with AXI manager access to unprotected SRAM reachable by Caliptra.\n\nThis issue affects Core ROM: 2.1.0 through 2.1.1.","status":"published","published":"2026-08-04T00:03:23.278Z","modified":"2026-08-04T21:25:26.656Z","cvss":[{"version":"4.0","score":5.6,"vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N","level":"medium","assessor":"cna"}],"cwes":["CWE-367","CWE-20"],"updated_at":"2026-11-02T14:20:05.15083Z"}],"euvd":[{"id":"EUVD-2026-52549","description":"Time-of-check time-of-use (TOCTOU) vulnerability combined with missing input validation in Caliptra Core ROM (UpdateResetFlow::run()) in subsystem mode allows a compromised local attacker to silently bypass secure boot by supplying an AXI staging address that is not validated against the strap-configured SS_EXTERNAL_STAGING_AREA_BASE_ADDR, enabling firmware to be modified between verification and loading into ICCM. Attestation continues to report the originally verified image digest, masking the compromise. Exploitation requires a compromised MCU firmware with AXI manager access to unprotected SRAM reachable by Caliptra.\n\nThis issue affects Core ROM: 2.1.0 through 2.1.1.","status":"published","published":"2026-08-04T00:03:23Z","modified":"2026-08-04T21:25:26Z","cvss":[{"version":"4.0","score":5.6,"vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N","level":"medium"}],"updated_at":"2026-11-02T18:02:22.516769Z"}],"nvd":[{"id":"CVE-2026-11835","description":"Time-of-check time-of-use (TOCTOU) vulnerability combined with missing input validation in Caliptra Core ROM (UpdateResetFlow::run()) in subsystem mode allows a compromised local attacker to silently bypass secure boot by supplying an AXI staging address that is not validated against the strap-configured SS_EXTERNAL_STAGING_AREA_BASE_ADDR, enabling firmware to be modified between verification and loading into ICCM. Attestation continues to report the originally verified image digest, masking the compromise. Exploitation requires a compromised MCU firmware with AXI manager access to unprotected SRAM reachable by Caliptra.\n\nThis issue affects Core ROM: 2.1.0 through 2.1.1.","status":"published","published":"2026-08-04T00:16:40.047Z","modified":"2026-10-23T23:10:00.157Z","cvss":[{"version":"4.0","score":5.7,"vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/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":"medium","assessor":"secondary"}],"cwes":["CWE-20","CWE-367"],"updated_at":"2026-11-02T14:12:34.643497Z"}],"osv":[{"id":"CVE-2026-11835","title":"Caliptra Update-Reset Secure-Boot Bypass via Attacker-Chosen AXI Staging Address (TOCTOU)","description":"Time-of-check time-of-use (TOCTOU) vulnerability combined with missing input validation in Caliptra Core ROM (UpdateResetFlow::run()) in subsystem mode allows a compromised local attacker to silently bypass secure boot by supplying an AXI staging address that is not validated against the strap-configured SS_EXTERNAL_STAGING_AREA_BASE_ADDR, enabling firmware to be modified between verification and loading into ICCM. Attestation continues to report the originally verified image digest, masking the compromise. Exploitation requires a compromised MCU firmware with AXI manager access to unprotected SRAM reachable by Caliptra.\n\nThis issue affects Core ROM: 2.1.0 through 2.1.1.","status":"published","published":"2026-08-04T00:03:23.278Z","modified":"2026-10-28T02:30:51.26084115Z","cvss":[{"version":"4.0","score":5.6,"vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-20","CWE-367"],"updated_at":"2026-11-02T15:44:57.008854Z"}]}}