{"id":"CVE-2021-3405","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-3405","generatedAt":"2026-10-27T22:26:01.248Z","title":"A heap overflow bug exists in the implementation of EbmlString::ReadData and EbmlUnicodeString::ReadData in libebml.","description":"A flaw was found in libebml before 1.4.2. A heap overflow bug exists in the implementation of EbmlString::ReadData and EbmlUnicodeString::ReadData in libebml.","published":"2021-02-23T20:15:12.000Z","lastModified":"2026-06-17T04:05:02.000Z","status":"Modified","sourceIdentifier":"secalert@redhat.com","cvss":{"version":"3.1","score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"},"cwe":["CWE-787"],"affected":["matroska/libebml","fedoraproject/fedora","debian/debian linux"],"epss":{"score":0.01729,"percentile":0.77422,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (1.73%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://github.com/Matroska-Org/libebml/issues/74","tags":["Exploit","Issue Tracking","Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://lists.debian.org/debian-lts-announce/2021/04/msg00016.html","tags":["Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JNHQI6MDOECJ2HT5GCLEX2DMJFEOWPW7/","source":"secalert@redhat.com"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UHIIMWZKHHELFF4NRDMOOCS3HKK3K4DF/","source":"secalert@redhat.com"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YY7R2JZRO5I6WS62KTJFTZGKYELVFTVB/","source":"secalert@redhat.com"},{"url":"https://security.gentoo.org/glsa/202208-21","tags":["Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://github.com/Matroska-Org/libebml/issues/74","tags":["Exploit","Issue Tracking","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2021/04/msg00016.html","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JNHQI6MDOECJ2HT5GCLEX2DMJFEOWPW7/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UHIIMWZKHHELFF4NRDMOOCS3HKK3K4DF/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YY7R2JZRO5I6WS62KTJFTZGKYELVFTVB/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.gentoo.org/glsa/202208-21","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-3405","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}