{"id":"UBUNTU-CVE-2026-34743","details":"XZ Utils provide a general-purpose data-compression library plus command-line tools. Prior to version 5.8.3, if lzma_index_decoder() was used to decode an Index that contained no Records, the resulting lzma_index was left in a state where where a subsequent lzma_index_append() would allocate too little memory, and a buffer overflow would occur. This issue has been patched in version 5.8.3.","modified":"2026-06-02T14:00:18.179184024Z","published":"2026-04-02T19:21:00Z","related":["USN-8362-1"],"upstream":["CVE-2026-34743"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-34743"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-34743"},{"type":"REPORT","url":"https://tukaani.org/xz/index-append-overflow.html"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8362-1"}],"affected":[{"package":{"name":"xz-utils","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/xz-utils?arch=source&distro=esm-infra-legacy%2Ftrusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1alpha+20120614-2ubuntu2.14.04.1+esm2"}]}],"versions":["5.1.1alpha+20120614-2ubuntu1","5.1.1alpha+20120614-2ubuntu2","5.1.1alpha+20120614-2ubuntu2.14.04.1+esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"liblzma5","binary_version":"5.1.1alpha+20120614-2ubuntu2.14.04.1+esm2"},{"binary_version":"5.1.1alpha+20120614-2ubuntu2.14.04.1+esm2","binary_name":"xz-utils"},{"binary_name":"xzdec","binary_version":"5.1.1alpha+20120614-2ubuntu2.14.04.1+esm2"}],"availability":"Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro","priority_reason":"Issue not likely to affect any real-world applications"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34743.json"}},{"package":{"name":"xz-utils","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/xz-utils?arch=source&distro=esm-infra-legacy%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.1.1alpha+20120614-2ubuntu2.16.04.1+esm2"}]}],"versions":["5.1.1alpha+20120614-2ubuntu2","5.1.1alpha+20120614-2ubuntu2.16.04.1+esm1"],"ecosystem_specific":{"priority_reason":"Issue not likely to affect any real-world applications","binaries":[{"binary_version":"5.1.1alpha+20120614-2ubuntu2.16.04.1+esm2","binary_name":"liblzma5"},{"binary_name":"xz-utils","binary_version":"5.1.1alpha+20120614-2ubuntu2.16.04.1+esm2"},{"binary_version":"5.1.1alpha+20120614-2ubuntu2.16.04.1+esm2","binary_name":"xzdec"}],"availability":"Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34743.json"}},{"package":{"name":"xz-utils","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/xz-utils?arch=source&distro=esm-infra%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.2.2-1.3ubuntu0.1+esm1"}]}],"versions":["5.2.2-1.3","5.2.2-1.3ubuntu0.1"],"ecosystem_specific":{"binaries":[{"binary_name":"liblzma5","binary_version":"5.2.2-1.3ubuntu0.1+esm1"},{"binary_name":"xz-utils","binary_version":"5.2.2-1.3ubuntu0.1+esm1"},{"binary_name":"xzdec","binary_version":"5.2.2-1.3ubuntu0.1+esm1"}],"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro","priority_reason":"Issue not likely to affect any real-world applications"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34743.json"}},{"package":{"name":"xz-utils","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/xz-utils?arch=source&distro=esm-infra%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.2.4-1ubuntu1.1+esm1"}]}],"versions":["5.2.4-1","5.2.4-1ubuntu1","5.2.4-1ubuntu1.1"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro","priority_reason":"Issue not likely to affect any real-world applications","binaries":[{"binary_version":"5.2.4-1ubuntu1.1+esm1","binary_name":"liblzma5"},{"binary_name":"xz-utils","binary_version":"5.2.4-1ubuntu1.1+esm1"},{"binary_name":"xzdec","binary_version":"5.2.4-1ubuntu1.1+esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34743.json"}},{"package":{"name":"xz-utils","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/xz-utils?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.2.5-2ubuntu1.1"}]}],"versions":["5.2.5-2","5.2.5-2build1","5.2.5-2build2","5.2.5-2ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_version":"5.2.5-2ubuntu1.1","binary_name":"liblzma5"},{"binary_name":"xz-utils","binary_version":"5.2.5-2ubuntu1.1"},{"binary_name":"xzdec","binary_version":"5.2.5-2ubuntu1.1"}],"availability":"No subscription required","priority_reason":"Issue not likely to affect any real-world applications"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34743.json"}},{"package":{"name":"xz-utils","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/xz-utils?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.6.1+really5.4.5-1ubuntu0.3"}]}],"versions":["5.4.1-0.2","5.4.4-0.1","5.4.5-0.1","5.4.5-0.3","5.6.0-0.2","5.6.1+really5.4.5-1","5.6.1+really5.4.5-1build0.1","5.6.1+really5.4.5-1ubuntu0.2"],"ecosystem_specific":{"binaries":[{"binary_name":"liblzma5","binary_version":"5.6.1+really5.4.5-1ubuntu0.3"},{"binary_name":"xz-utils","binary_version":"5.6.1+really5.4.5-1ubuntu0.3"},{"binary_name":"xzdec","binary_version":"5.6.1+really5.4.5-1ubuntu0.3"}],"availability":"No subscription required","priority_reason":"Issue not likely to affect any real-world applications"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34743.json"}},{"package":{"name":"xz-utils","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/xz-utils?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.8.1-1ubuntu0.1"}]}],"versions":["5.6.4-1ubuntu1","5.8.1-1","5.8.1-1build1","5.8.1-1build2"],"ecosystem_specific":{"priority_reason":"Issue not likely to affect any real-world applications","binaries":[{"binary_name":"liblzma5","binary_version":"5.8.1-1ubuntu0.1"},{"binary_name":"xz-utils","binary_version":"5.8.1-1ubuntu0.1"},{"binary_version":"5.8.1-1ubuntu0.1","binary_name":"xzdec"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34743.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"},{"type":"Ubuntu","score":"low"}]}