{"id":"UBUNTU-CVE-2026-23901","details":"Observable Timing Discrepancy vulnerability in Apache Shiro. This issue affects Apache Shiro: from 1.*, 2.* before 2.0.7. Users are recommended to upgrade to version 2.0.7 or later, which fixes the issue. Prior to Shiro 2.0.7, code paths for non-existent vs. existing users are different enough, that a brute-force attack may be able to tell, by timing the requests only, determine if the request failed because of a non-existent user vs. wrong password. The most likely attack vector is a local attack only. Shiro security model https://shiro.apache.org/security-model.html#username_enumeration  discusses this as well. Typically, brute force attack can be mitigated at the infrastructure level.","modified":"2026-05-20T16:12:11.116549652Z","published":"2026-02-10T10:15:00Z","upstream":["CVE-2026-23901"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-23901"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-23901"},{"type":"REPORT","url":"https://www.openwall.com/lists/oss-security/2026/02/08/2"}],"affected":[{"package":{"name":"shiro","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/shiro?arch=source&distro=esm-apps%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.4-1","1.2.4-1ubuntu0.1~esm1","1.2.4-1ubuntu0.1~esm2"],"ecosystem_specific":{"binaries":[{"binary_version":"1.2.4-1ubuntu0.1~esm2","binary_name":"libshiro-java"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23901.json"}},{"package":{"name":"shiro","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/shiro?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-2","1.3.2-3~18.04","1.3.2-3~18.04.1","1.3.2-3ubuntu0.18.04.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libshiro-java","binary_version":"1.3.2-3ubuntu0.18.04.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23901.json"}},{"package":{"name":"shiro","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/shiro?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-4","1.3.2-4ubuntu0.1","1.3.2-4ubuntu0.2"],"ecosystem_specific":{"binaries":[{"binary_version":"1.3.2-4ubuntu0.2","binary_name":"libshiro-java"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23901.json"}},{"package":{"name":"shiro","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/shiro?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-4","1.3.2-5"],"ecosystem_specific":{"binaries":[{"binary_version":"1.3.2-5","binary_name":"libshiro-java"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23901.json"}},{"package":{"name":"shiro","ecosystem":"Ubuntu:Pro:24.04:LTS","purl":"pkg:deb/ubuntu/shiro?arch=source&distro=esm-apps%2Fnoble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-5","1.3.2-5ubuntu0.24.04.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libshiro-java","binary_version":"1.3.2-5ubuntu0.24.04.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23901.json"}},{"package":{"name":"shiro","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/shiro?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-6ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.3.2-6ubuntu1","binary_name":"libshiro-java"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23901.json"}},{"package":{"name":"shiro","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/shiro?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-6ubuntu1","1.3.2-6ubuntu2"],"ecosystem_specific":{"binaries":[{"binary_name":"libshiro-java","binary_version":"1.3.2-6ubuntu2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-23901.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:A/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N/S:N/AU:Y/R:A/V:C/RE:L/U:Green"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N"},{"type":"Ubuntu","score":"medium"}]}