{"id":"CVE-2018-16253","details":"In sig_verify() in x509.c in axTLS version 2.1.3 and before, the PKCS#1 v1.5 signature verification does not properly verify the ASN.1 metadata. Consequently, a remote attacker can forge signatures when small public exponents are being used, which could lead to impersonation through fake X.509 certificates. This is an even more permissive variant of CVE-2006-4790 and CVE-2014-1568.","modified":"2026-04-11T12:27:49.872989Z","published":"2018-11-07T20:29:00.667Z","references":[{"type":"FIX","url":"https://github.com/igrr/axtls-8266/commit/5efe2947ab45e81d84b5f707c51d1c64be52f36c"},{"type":"EVIDENCE","url":"https://sourceforge.net/p/axtls/mailman/message/36459928/"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/igrr/axtls-8266","events":[{"introduced":"0"},{"fixed":"5efe2947ab45e81d84b5f707c51d1c64be52f36c"}]},{"type":"GIT","repo":"https://github.com/igrr/axtls-8266","events":[{"introduced":"0"},{"fixed":"5efe2947ab45e81d84b5f707c51d1c64be52f36c"}]}],"database_specific":{"vanir_signatures_modified":"2026-04-11T12:27:49Z","source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2018-16253.json","unresolved_ranges":[{"events":[{"introduced":"0"},{"last_affected":"2.1.3"}]},{"events":[{"introduced":"0"},{"last_affected":"fake"}]}],"vanir_signatures":[{"source":"https://github.com/igrr/axtls-8266/commit/5efe2947ab45e81d84b5f707c51d1c64be52f36c","digest":{"line_hashes":["108661851987972133158347054716703460683","14896255174603763604770523751983435879","120240012124074572250753975559093603406","45010925886924942386907557492617314856","115305286616551607897244325241390183963","9084237671732349361622604103010111563","185845852160614897619048903410496139504","208322761451658317154631074413909015154","185082032209968563001193921342815963010","186270198572434066780252391661755022115","50486728262798664783477895502371598539","238538377523240267513329349303468711107","244601293052885541233433686491443506785","57107941115571653783496538010191647563","218390482235484409823204904791605352948","278618590998667647087943783369648520885","166932922021684597834217713555700614848","195146750242824880305351287025864433794","22185783351391265490991248551830443790","84577917608870377487401127617600840478","181807139630374287586913659774436982587","57536454303877057962146740463074587417","233082035197181483690985219850815497923","258752981139989151020579234742060642985","117578550962584056793915946910351421511","61491189147592498635277465718922381231","108836589434530459216980942412049144973","335081944872175553627843886622382730268","95625288284106286882967882031022885083","49585425216726811453278729953818840069","237978599236179955971782873432814558865","339536106570935589585141430302204605375","294128945153324378199602375625233392002","202780183330052102017085865184175332675","235316235711897240953832705127279614660","19322163383816135294590054626317666890","149134396912841586962585068550949712513","154871753701657350703814844030645535224","138740526242742065281847547013745442303","236008771591026412195639438620995675865","303492404983386076464265066061129154306","93317831494390685477701447882423156453","165379616122019241837551638587367351881","165877849408296707887289760177956569788","260572460417766524035127727657875885064","15599565959541491860649101577670499488","285410099532478080544838165762270161618"],"threshold":0.9},"target":{"file":"ssl/x509.c"},"signature_version":"v1","id":"CVE-2018-16253-3090bf7e","deprecated":false,"signature_type":"Line"},{"source":"https://github.com/igrr/axtls-8266/commit/5efe2947ab45e81d84b5f707c51d1c64be52f36c","digest":{"length":389,"function_hash":"74073868604478741200156603912144804076"},"target":{"function":"get_signature","file":"ssl/x509.c"},"signature_version":"v1","id":"CVE-2018-16253-94fc8e4b","deprecated":false,"signature_type":"Function"},{"source":"https://github.com/igrr/axtls-8266/commit/5efe2947ab45e81d84b5f707c51d1c64be52f36c","digest":{"line_hashes":["253007544034811596310265824059848257290","268133784929346848139382881450918463779","65170034753240938602689110438809907804","4989148451732204170605134390826381115"],"threshold":0.9},"target":{"file":"ssl/os_port.h"},"signature_version":"v1","id":"CVE-2018-16253-c256e85e","deprecated":false,"signature_type":"Line"},{"source":"https://github.com/igrr/axtls-8266/commit/5efe2947ab45e81d84b5f707c51d1c64be52f36c","digest":{"length":702,"function_hash":"232285230700911005501498625380349597162"},"target":{"function":"sig_verify","file":"ssl/x509.c"},"signature_version":"v1","id":"CVE-2018-16253-d6e58869","deprecated":false,"signature_type":"Function"},{"source":"https://github.com/igrr/axtls-8266/commit/5efe2947ab45e81d84b5f707c51d1c64be52f36c","digest":{"length":2514,"function_hash":"47102076113973104952396175716829351788"},"target":{"function":"x509_verify","file":"ssl/x509.c"},"signature_version":"v1","id":"CVE-2018-16253-ec948ef3","deprecated":false,"signature_type":"Function"}]}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N"}]}