{"id":"CVE-2020-36478","details":"An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). A NULL algorithm parameters entry looks identical to an array of REAL (size zero) and thus the certificate is considered valid. However, if the parameters do not match in any way, then the certificate should be considered invalid.","modified":"2026-04-02T06:09:54.513849Z","published":"2021-08-23T02:15:07.097Z","references":[{"type":"ADVISORY","url":"https://github.com/ARMmbed/mbedtls/releases/tag/v2.25.0"},{"type":"ADVISORY","url":"https://github.com/ARMmbed/mbedtls/releases/tag/v2.7.18"},{"type":"ADVISORY","url":"https://lists.debian.org/debian-lts-announce/2021/11/msg00021.html"},{"type":"ADVISORY","url":"https://lists.debian.org/debian-lts-announce/2022/12/msg00036.html"},{"type":"ADVISORY","url":"https://github.com/ARMmbed/mbedtls/releases/tag/v2.16.9"},{"type":"FIX","url":"https://cert-portal.siemens.com/productcert/pdf/ssa-756638.pdf"},{"type":"EVIDENCE","url":"https://github.com/ARMmbed/mbedtls/issues/3629"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/armmbed/mbedtls","events":[{"introduced":"0"},{"fixed":"78d9663acec4ac72af43e2db57fc73a24e856108"},{"introduced":"8be0e6db41b4a085e90cb03983f99d3a5158d450"},{"fixed":"3fac0bae4a50113989b3d015cd2d948f51a6d9ac"},{"introduced":"3f8d78411a26e833db18d9fbde0e2f0baeda87f0"},{"fixed":"1c54b5410fd48d6bcada97e30cac417c5c7eea67"},{"introduced":"0"},{"fixed":"8254ed2a9fadede8c6bf414072f78fc78d5af61c"},{"introduced":"0"},{"fixed":"8254ed2a9fadede8c6bf414072f78fc78d5af61c"}],"database_specific":{"versions":[{"introduced":"0"},{"fixed":"2.7.18"},{"introduced":"2.8.0"},{"fixed":"2.16.9"},{"introduced":"2.17.0"},{"fixed":"2.25.0"},{"introduced":"0"},{"fixed":"2.2"},{"introduced":"0"},{"fixed":"2.2"}]}},{"type":"GIT","repo":"https://github.com/mbed-tls/mbedtls","events":[{"introduced":"0"},{"fixed":"3fac0bae4a50113989b3d015cd2d948f51a6d9ac"},{"fixed":"1c54b5410fd48d6bcada97e30cac417c5c7eea67"},{"fixed":"78d9663acec4ac72af43e2db57fc73a24e856108"}]}],"versions":["beta-oob-2","beta-release","feature-opaque-keys-2.7-rc1","list","mbed-alpha3","mbed-os-beta","mbedos-16.01-release","mbedos-16.03-release","mbedos-2016q1-oob1","mbedos-2016q1-oob2","mbedos-2016q1-oob3","mbedos-release-15-11","mbedos-techcon-oob2","mbedtls-1.3.10","mbedtls-1.3.11","mbedtls-1.3.12","mbedtls-1.3.13","mbedtls-1.3.14","mbedtls-1.3.15","mbedtls-1.3.16","mbedtls-1.3.17","mbedtls-1.3.18","mbedtls-1.3.19","mbedtls-1.3.19-rc1","mbedtls-1.3.20","mbedtls-1.3.21","mbedtls-1.3.21-rc1","mbedtls-1.3.22","mbedtls-1.3.22-rc1","mbedtls-1.4-dtls-preview","mbedtls-2.0.0","mbedtls-2.1.0","mbedtls-2.1.1","mbedtls-2.1.10","mbedtls-2.1.10-rc1","mbedtls-2.1.11","mbedtls-2.1.11-rc1","mbedtls-2.1.12","mbedtls-2.1.13","mbedtls-2.1.14","mbedtls-2.1.15","mbedtls-2.1.16","mbedtls-2.1.17","mbedtls-2.1.18","mbedtls-2.1.2","mbedtls-2.1.3","mbedtls-2.1.4","mbedtls-2.1.5","mbedtls-2.1.6","mbedtls-2.1.7","mbedtls-2.1.7-rc1","mbedtls-2.1.8","mbedtls-2.1.9","mbedtls-2.1.9-rc1","mbedtls-2.10.0","mbedtls-2.11.0","mbedtls-2.12.0","mbedtls-2.13.0","mbedtls-2.13.1","mbedtls-2.14.0","mbedtls-2.14.1","mbedtls-2.15.0","mbedtls-2.15.1","mbedtls-2.16.0","mbedtls-2.16.1","mbedtls-2.16.2","mbedtls-2.16.3","mbedtls-2.16.4","mbedtls-2.16.5","mbedtls-2.16.6","mbedtls-2.16.7","mbedtls-2.16.8","mbedtls-2.17.0","mbedtls-2.18.0","mbedtls-2.18.1","mbedtls-2.19.0","mbedtls-2.19.0d1","mbedtls-2.19.0d2","mbedtls-2.19.1","mbedtls-2.2.0","mbedtls-2.2.1","mbedtls-2.20.0","mbedtls-2.20.0d0","mbedtls-2.20.0d1","mbedtls-2.21.0","mbedtls-2.22.0","mbedtls-2.22.0d0","mbedtls-2.23.0","mbedtls-2.24.0","mbedtls-2.3.0","mbedtls-2.4.0","mbedtls-2.4.1","mbedtls-2.4.2","mbedtls-2.4.2-rc1","mbedtls-2.5.0","mbedtls-2.5.0-rc1","mbedtls-2.5.1","mbedtls-2.6.0","mbedtls-2.6.0-rc1","mbedtls-2.6.1","mbedtls-2.6.1-rc1","mbedtls-2.7.0","mbedtls-2.7.0-rc1","mbedtls-2.7.1","mbedtls-2.7.10","mbedtls-2.7.11","mbedtls-2.7.12","mbedtls-2.7.13","mbedtls-2.7.14","mbedtls-2.7.15","mbedtls-2.7.16","mbedtls-2.7.17","mbedtls-2.7.2","mbedtls-2.7.2-rc1","mbedtls-2.7.3","mbedtls-2.7.4","mbedtls-2.7.5","mbedtls-2.7.6","mbedtls-2.7.7","mbedtls-2.7.8","mbedtls-2.7.9","mbedtls-2.8.0","mbedtls-2.8.0-rc1","mbedtls-2.9.0","mbedtls-3.0.0p1","polarssl-0.10.0","polarssl-0.10.1","polarssl-0.11.0","polarssl-0.11.1","polarssl-0.12.0","polarssl-0.12.1","polarssl-0.13.0","polarssl-0.13.1","polarssl-0.14.0","polarssl-0.14.1","polarssl-0.14.2","polarssl-0.14.3","polarssl-0.99-pre1","polarssl-0.99-pre2","polarssl-0.99-pre3","polarssl-0.99-pre4","polarssl-0.99-pre5","polarssl-1.0.0","polarssl-1.1.0","polarssl-1.1.0-rc0","polarssl-1.1.0-rc1","polarssl-1.1.1","polarssl-1.1.2","polarssl-1.1.3","polarssl-1.1.4","polarssl-1.1.5","polarssl-1.1.6","polarssl-1.1.7","polarssl-1.1.8","polarssl-1.2.0","polarssl-1.2.0-pre1","polarssl-1.2.1","polarssl-1.2.10","polarssl-1.2.11","polarssl-1.2.12","polarssl-1.2.13","polarssl-1.2.14","polarssl-1.2.15","polarssl-1.2.16","polarssl-1.2.17","polarssl-1.2.18","polarssl-1.2.19","polarssl-1.2.2","polarssl-1.2.3","polarssl-1.2.4","polarssl-1.2.5","polarssl-1.2.6","polarssl-1.2.7","polarssl-1.2.8","polarssl-1.2.9","polarssl-1.3-alpha1","polarssl-1.3.0","polarssl-1.3.0-rc0","polarssl-1.3.1","polarssl-1.3.2","polarssl-1.3.3","polarssl-1.3.4","polarssl-1.3.5","polarssl-1.3.6","polarssl-1.3.7",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