CVE-2026-20421

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-20421", "assignerOrgId": "ee979b05-11f8-4f25-a7e0-a1fa9c190374", "state": "PUBLISHED", "assignerShortName": "MediaTek", "dateReserved": "2025-11-03T01:30:59.010Z", "datePublished": "2026-02-02T08:14:41.044Z", "dateUpdated": "2026-03-30T13:02:38.436Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "ee979b05-11f8-4f25-a7e0-a1fa9c190374", "shortName": "MediaTek", "dateUpdated": "2026-03-30T13:02:38.436Z"}, "descriptions": [{"lang": "en", "value": "In Modem, there is a possible system crash due to improper input validation. This could lead to remote denial of service, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: MOLY01738293; Issue ID: MSV-5922."}], "affected": [{"vendor": "MediaTek, Inc.", "product": "MediaTek chipset", "defaultStatus": "unaffected", "versions": [{"version": "MT2735", "status": "affected"}, {"version": "MT6833", "status": "affected"}, {"version": "MT6853", "status": "affected"}, {"version": "MT6855", "status": "affected"}, {"version": "MT6873", "status": "affected"}, {"version": "MT6875", "status": "affected"}, {"version": "MT6877", "status": "affected"}, {"version": "MT6880", "status": "affected"}, {"version": "MT6883", "status": "affected"}, {"version": "MT6885", "status": "affected"}, {"version": "MT6889", "status": "affected"}, {"version": "MT6890", "status": "affected"}, {"version": "MT6891", "status": "affected"}, {"version": "MT6893", "status": "affected"}, {"version": "MT8791", "status": "affected"}]}], "references": [{"url": "https://corp.mediatek.com/product-security-bulletin/February-2026"}], "problemTypes": [{"descriptions": [{"type": "CWE", "lang": "en", "cweId": "CWE-125", "description": "CWE-125 Out-of-bounds Read"}]}], "x_generator": {"engine": "cvelib 1.8.0"}}, "adp": [{"metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 6.5, "attackVector": "ADJACENT_NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}}, {"other": {"type": "ssvc", "content": {"timestamp": "2026-02-17T14:16:27.641367Z", "id": "CVE-2026-20421", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-02-17T14:16:39.870Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 6.5, "attackVector": "ADJACENT_NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}}, {"other": {"type": "ssvc", "content": {"id": "CVE-2026-20421", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-02-17T14:16:27.641367Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-02-02T21:25:12.729Z"}}], "cna": {"affected": [{"vendor": "MediaTek, Inc.", "product": "MediaTek chipset", "versions": [{"status": "affected", "version": "MT2735"}, {"status": "affected", "version": "MT6833"}, {"status": "affected", "version": "MT6853"}, {"status": "affected", "version": "MT6855"}, {"status": "affected", "version": "MT6873"}, {"status": "affected", "version": "MT6875"}, {"status": "affected", "version": "MT6877"}, {"status": "affected", "version": "MT6880"}, {"status": "affected", "version": "MT6883"}, {"status": "affected", "version": "MT6885"}, {"status": "affected", "version": "MT6889"}, {"status": "affected", "version": "MT6890"}, {"status": "affected", "version": "MT6891"}, {"status": "affected", "version": "MT6893"}, {"status": "affected", "version": "MT8791"}], "defaultStatus": "unaffected"}], "references": [{"url": "https://corp.mediatek.com/product-security-bulletin/February-2026"}], "x_generator": {"engine": "cvelib 1.8.0"}, "descriptions": [{"lang": "en", "value": "In Modem, there is a possible system crash due to improper input validation. This could lead to remote denial of service, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: MOLY01738293; Issue ID: MSV-5922."}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-125", "description": "CWE-125 Out-of-bounds Read"}]}], "providerMetadata": {"orgId": "ee979b05-11f8-4f25-a7e0-a1fa9c190374", "shortName": "MediaTek", "dateUpdated": "2026-03-30T13:02:38.436Z"}}}, "cveMetadata": {"cveId": "CVE-2026-20421", "state": "PUBLISHED", "dateUpdated": "2026-03-30T13:02:38.436Z", "dateReserved": "2025-11-03T01:30:59.010Z", "assignerOrgId": "ee979b05-11f8-4f25-a7e0-a1fa9c190374", "datePublished": "2026-02-02T08:14:41.044Z", "assignerShortName": "MediaTek"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "MediaTek chipset", "vendor": "MediaTek, Inc.", "versions": [{"status": "affected", "version": "MT2735"}, {"status": "affected", "version": "MT6833"}, {"status": "affected", "version": "MT6853"}, {"status": "affected", "version": "MT6855"}, {"status": "affected", "version": "MT6873"}, {"status": "affected", "version": "MT6875"}, {"status": "affected", "version": "MT6877"}, {"status": "affected", "version": "MT6880"}, {"status": "affected", "version": "MT6883"}, {"status": "affected", "version": "MT6885"}, {"status": "affected", "version": "MT6889"}, {"status": "affected", "version": "MT6890"}, {"status": "affected", "version": "MT6891"}, {"status": "affected", "version": "MT6893"}, {"status": "affected", "version": "MT8791"}]}], "source": "security@mediatek.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:mediatek:nr15:-:*:*:*:*:*:*:*", "matchCriteriaId": "E30A2D2E-6A72-4070-A471-EEE75F7D07F2", "vulnerable": true}], "negate": false, "operator": "OR"}, {"cpeMatch": [{"criteria": "cpe:2.3:h:mediatek:mt2735:-:*:*:*:*:*:*:*", "matchCriteriaId": "7F1D09FC-5BE9-4B23-82F1-3C6EAC5711A6", "vulnerable": false}, {"criteria": "cpe:2.3:h:mediatek:mt6833:-:*:*:*:*:*:*:*", "matchCriteriaId": "9814939B-F05E-4870-90C0-7C0F6BAAEB39", "vulnerable": false}, {"criteria": "cpe:2.3:h:mediatek:mt6853:-:*:*:*:*:*:*:*", "matchCriteriaId": "366F1912-756B-443E-9962-224937DD7DFB", "vulnerable": false}, {"criteria": "cpe:2.3:h:mediatek:mt6855:-:*:*:*:*:*:*:*", "matchCriteriaId": "89AFEE24-7AAD-4EDB-8C3E-EDBA3240730A", "vulnerable": false}, {"criteria": "cpe:2.3:h:mediatek:mt6873:-:*:*:*:*:*:*:*", "matchCriteriaId": "F6B8A36E-C5FB-44AE-A1C3-50EBF4C68F6B", "vulnerable": false}, {"criteria": "cpe:2.3:h:mediatek:mt6875:-:*:*:*:*:*:*:*", "matchCriteriaId": "80BDC5EC-E822-4BC7-8C0D-E8AD8396E8FE", "vulnerable": false}, {"criteria": "cpe:2.3:h:mediatek:mt6877:-:*:*:*:*:*:*:*", "matchCriteriaId": "7CA9352F-E9BD-4656-9B7C-4AFEE2C78E58", "vulnerable": false}, {"criteria": "cpe:2.3:h:mediatek:mt6880:-:*:*:*:*:*:*:*", "matchCriteriaId": "68CF4A7A-3136-4C4C-A795-81323896BE11", "vulnerable": false}, {"criteria": "cpe:2.3:h:mediatek:mt6883:-:*:*:*:*:*:*:*", "matchCriteriaId": "15E2EC3F-9FB3-488B-B1C1-2793A416C755", "vulnerable": false}, {"criteria": "cpe:2.3:h:mediatek:mt6885:-:*:*:*:*:*:*:*", "matchCriteriaId": "DD64413C-C774-4C4F-9551-89E1AA9469EE", "vulnerable": false}, {"criteria": "cpe:2.3:h:mediatek:mt6889:-:*:*:*:*:*:*:*", "matchCriteriaId": "3B787DC3-8E5A-4968-B20B-37B6257FAAE2", "vulnerable": false}, {"criteria": "cpe:2.3:h:mediatek:mt6890:-:*:*:*:*:*:*:*", "matchCriteriaId": "171D1C08-F055-44C0-913C-AA2B73AF5B72", "vulnerable": false}, {"criteria": "cpe:2.3:h:mediatek:mt6891:-:*:*:*:*:*:*:*", "matchCriteriaId": "D8E91CA4-CA5B-40D1-9A96-2B875104BCF4", "vulnerable": false}, {"criteria": "cpe:2.3:h:mediatek:mt6893:-:*:*:*:*:*:*:*", "matchCriteriaId": "213B5C7F-D965-4312-9CDF-4F06FA77D401", "vulnerable": false}, {"criteria": "cpe:2.3:h:mediatek:mt8791:-:*:*:*:*:*:*:*", "matchCriteriaId": "9CD2C3EC-B62D-4616-964F-FDBE5B14A449", "vulnerable": false}], "negate": false, "operator": "OR"}], "operator": "AND"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In Modem, there is a possible system crash due to improper input validation. This could lead to remote denial of service, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: MOLY01738293; Issue ID: MSV-5922."}, {"lang": "es", "value": "En el m\u00f3dem, existe una posible ca\u00edda del sistema debido a una validaci\u00f3n de entrada incorrecta. Esto podr\u00eda llevar a una denegaci\u00f3n de servicio remota, si un UE se ha conectado a una estaci\u00f3n base maliciosa controlada por el atacante, sin necesidad de privilegios de ejecuci\u00f3n adicionales. No se necesita interacci\u00f3n del usuario para la explotaci\u00f3n. ID del parche: MOLY01738293; ID del problema: MSV-5922."}], "id": "CVE-2026-20421", "lastModified": "2026-06-17T10:17:24.320", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "ADJACENT_NETWORK", "availabilityImpact": "HIGH", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 3.6, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-20421", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-02-17T14:16:27.641367Z", "version": "2.0.3"}}]}, "published": "2026-02-02T09:15:57.257", "references": [{"source": "security@mediatek.com", "tags": ["Vendor Advisory"], "url": "https://corp.mediatek.com/product-security-bulletin/February-2026"}], "sourceIdentifier": "security@mediatek.com", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-125"}], "source": "security@mediatek.com", "type": "Secondary"}]}

{}

{"analysis": {"en": {"generated_at": "2026-04-16T07:13:42.230521+00:00", "value": {"mitigation_remediation": ["Apply the vendor patch identified by MOLY01738293 to the MediaTek chipset firmware.", "Upgrade all MediaTek-based devices to the latest supported firmware that incorporates the patch.", "If a patch is not yet available, block connections to unverified base stations by enforcing strict base station authentication and monitoring for abnormal RRC messages."], "summary": {"action": "Immediate Patch", "impact": "Remote Denial of Service"}, "threat_synthesis": {"affected_systems": "The affected products are MediaTek chipsets, including models mt2735, mt6833, mt6853, mt6855, mt6873, mt6875, mt6877, mt6880, mt6883, mt6885, mt6889, mt6890, mt6891, mt6893, mt8791, and the legacy NR15 operating environment. No specific firmware version is disclosed in the advisory.", "description_and_impact": "A Modem input validation flaw can trigger a system crash, leading to remote denial of service.\nThe vulnerability does not require any special privileges or user interaction and is classified as a buffer over-read (CWE-125).", "risk_and_exploitability": "The CVSS score is 6.5, indicating moderate severity, while the EPSS is below 1\u202f%, implying a very low likelihood of exploitation, and the vulnerability is not listed in CISA\u2019s Known Exploited Vulnerabilities catalog.\nExploitation can occur when a user equipment device connects to a rogue base station controlled by an attacker. No additional privileges or user interaction are required; the attacker simply induces a modem crash that disables network connectivity for the target device.\nThe likely attack vector is remote, via the radio interface between the device and the compromised base station, and it is inferred from the description that the attack can be conducted over the air without physical access."}}}}, "created": "2026-02-04T12:45:06.150093+00:00", "title": "Modem Input Validation Crash Causing Remote Denial of Service via Rogue Base Station", "updated": "2026-04-16T07:15:28.178428+00:00", "vendors": ["mediatek", "mediatek$PRODUCT$mt2735", "mediatek$PRODUCT$mt6833", "mediatek$PRODUCT$mt6853", "mediatek$PRODUCT$mt6855", "mediatek$PRODUCT$mt6873", "mediatek$PRODUCT$mt6875", "mediatek$PRODUCT$mt6877", "mediatek$PRODUCT$mt6880", "mediatek$PRODUCT$mt6883", "mediatek$PRODUCT$mt6885", "mediatek$PRODUCT$mt6889", "mediatek$PRODUCT$mt6890", "mediatek$PRODUCT$mt6891", "mediatek$PRODUCT$mt6893", "mediatek$PRODUCT$mt8791"]}