{"id":"CVE-2026-23901","aliases":["DEBIAN-CVE-2026-23901","EUVD-2026-6879","GHSA-c4qc-4q9p-m9q9","UBUNTU-CVE-2026-23901"],"status":"published","title":"Apache Shiro: Brute force attack possible to determine valid user names","description":"Observable Timing Discrepancy vulnerability in Apache Shiro.\n\nThis issue affects Apache Shiro: from 1.*, 2.* before 2.0.7.\n\nUsers are recommended to upgrade to version 2.0.7 or later, which fixes the issue.\n\nPrior to Shiro 2.0.7, code paths for non-existent vs. existing users are different enough,\nthat a brute-force attack may be able to tell, by timing the requests only, determine if\nthe request failed because of a non-existent user vs. wrong password.\n\nThe most likely attack vector is a local attack only.\nShiro security model  https://shiro.apache.org/security-model.html#username_enumeration  discusses this as well.\n\nTypically, brute force attack can be mitigated at the infrastructure level.","severity":{"version":"4.0","score":1,"vector":"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","level":"low","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.0023,"percentile":0.1396,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-208"],"published":"2026-02-10T09:25:51Z","modified":"2026-10-17T12:59:55Z","fixes":[{"ecosystem":"Maven","package":"org.apache.shiro:shiro-core","fixed_in":["2.1.0"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Maven","package":"org.apache.shiro:shiro-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.1.0"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"shiro","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-5","1.3.2-6"]},{"source":"osv","ecosystem":"Debian:13","package":"shiro","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-6"]},{"source":"osv","ecosystem":"Debian:14","package":"shiro","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-6"]},{"source":"osv","ecosystem":"Maven","package":"org.apache.shiro:shiro-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.1.0"}]}],"versions":["1.0.0-incubating","1.1.0","1.10.0","1.10.1","1.11.0","1.12.0","1.13.0","1.2.0","1.2.1","1.2.2","1.2.3","1.2.4","1.2.5","1.2.6","1.3.0","1.3.1","1.3.2","1.4.0","1.4.0-RC2","1.4.1","1.4.2","1.5.0","1.5.1","1.5.2","1.5.3","1.6.0","1.7.0","1.7.1","1.8.0","1.9.0","1.9.1","2.0.0","2.0.0-alpha-1","2.0.0-alpha-2","2.0.0-alpha-3","2.0.0-alpha-4","2.0.1","2.0.2","2.0.3","2.0.4","2.0.5","2.0.6"]},{"source":"osv","ecosystem":"Ubuntu:Pro:16.04:LTS","package":"shiro","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.4-1","1.2.4-1ubuntu0.1~esm1","1.2.4-1ubuntu0.1~esm2"]},{"source":"osv","ecosystem":"Ubuntu:Pro:18.04:LTS","package":"shiro","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"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"shiro","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-4","1.3.2-4ubuntu0.1","1.3.2-4ubuntu0.2"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"shiro","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-4","1.3.2-5"]},{"source":"osv","ecosystem":"Ubuntu:Pro:24.04:LTS","package":"shiro","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-5","1.3.2-5ubuntu0.24.04.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"shiro","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-6ubuntu1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"shiro","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-6ubuntu2"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"shiro","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.2-6ubuntu1","1.3.2-6ubuntu2"]}],"products":[{"vendor":"apache","product":"shiro"},{"vendor":"apache software foundation","product":"apache shiro"}],"references":[{"url":"https://lists.apache.org/thread/mm1jct9b86jvnh3y44tj22xvjtx3xhhh","tags":["vendor-advisory","Issue Tracking","Mailing List","Third Party Advisory","report","web"]},{"url":"http://www.openwall.com/lists/oss-security/2026/02/08/2","tags":["Mailing List","Third Party Advisory","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23901","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-c4qc-4q9p-m9q9"},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-23901","tags":["advisory"]},{"url":"https://github.com/apache/shiro","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2026-23901","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-23901","tags":["report"]},{"url":"https://www.openwall.com/lists/oss-security/2026/02/08/2","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-23901","title":"Apache Shiro: Brute force attack possible to determine valid user names","description":"Observable Timing Discrepancy vulnerability in Apache Shiro.\n\nThis issue affects Apache Shiro: from 1.*, 2.* before 2.0.7.\n\nUsers are recommended to upgrade to version 2.0.7 or later, which fixes the issue.\n\nPrior to Shiro 2.0.7, code paths for non-existent vs. existing users are different enough,\nthat a brute-force attack may be able to tell, by timing the requests only, determine if\nthe request failed because of a non-existent user vs. wrong password.\n\nThe most likely attack vector is a local attack only.\nShiro security model  https://shiro.apache.org/security-model.html#username_enumeration  discusses this as well.\n\nTypically, brute force attack can be mitigated at the infrastructure level.","status":"published","published":"2026-02-10T09:25:51.765Z","modified":"2026-02-10T15:31:25.166Z","cvss":[{"version":"4.0","score":1,"vector":"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","level":"low","assessor":"cna"}],"cwes":["CWE-208"],"updated_at":"2026-11-02T13:42:15.603999Z"}],"euvd":[{"id":"EUVD-2026-6879","description":"Observable Timing Discrepancy vulnerability in Apache Shiro.\n\nThis issue affects Apache Shiro: from 1.*, 2.* before 2.0.7.\n\nUsers are recommended to upgrade to version 2.0.7 or later, which fixes the issue.\n\nPrior to Shiro 2.0.7, code paths for non-existent vs. existing users are different enough,\nthat a brute-force attack may be able to tell, by timing the requests only, determine if\nthe request failed because of a non-existent user vs. wrong password.\n\nThe most likely attack vector is a local attack only.\nShiro security model  https://shiro.apache.org/security-model.html#username_enumeration  discusses this as well.\n\nTypically, brute force attack can be mitigated at the infrastructure level.","status":"published","published":"2026-02-10T09:25:51Z","modified":"2026-02-10T15:31:25Z","cvss":[{"version":"4.0","score":1,"vector":"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","level":"low"}],"updated_at":"2026-11-02T19:48:42.087959Z"}],"ghsa":[{"id":"GHSA-c4qc-4q9p-m9q9","title":"Apache Shiro Affected by an Observable Timing Discrepancy Vulnerability","description":"Observable Timing Discrepancy vulnerability in Apache Shiro.\n\nThis issue affects Apache Shiro: from 1.*, 2.* before 2.0.7.\n\nUsers are recommended to upgrade to version 2.0.7 or later, which fixes the issue.\n\nPrior to Shiro 2.0.7, code paths for non-existent vs. existing users are different enough,\nthat a brute-force attack may be able to tell, by timing the requests only, determine if\nthe request failed because of a non-existent user vs. wrong password.\n\nThe most likely attack vector is a local attack only.\nShiro security model  https://shiro.apache.org/security-model.html#username_enumeration  discusses this as well.\n\nTypically, brute force attack can be mitigated at the infrastructure level.","status":"published","published":"2026-02-10T12:30:28Z","modified":"2026-02-10T14:33:36Z","cvss":[{"version":"4.0","score":1,"vector":"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","level":"low"}],"cwes":["CWE-208"],"updated_at":"2026-11-02T14:39:24.742346Z"}],"nvd":[{"id":"CVE-2026-23901","description":"Observable Timing Discrepancy vulnerability in Apache Shiro.\n\nThis issue affects Apache Shiro: from 1.*, 2.* before 2.0.7.\n\nUsers are recommended to upgrade to version 2.0.7 or later, which fixes the issue.\n\nPrior to Shiro 2.0.7, code paths for non-existent vs. existing users are different enough,\nthat a brute-force attack may be able to tell, by timing the requests only, determine if\nthe request failed because of a non-existent user vs. wrong password.\n\nThe most likely attack vector is a local attack only.\nShiro security model  https://shiro.apache.org/security-model.html#username_enumeration  discusses this as well.\n\nTypically, brute force attack can be mitigated at the infrastructure level.","status":"published","published":"2026-02-10T10:15:59.24Z","modified":"2026-06-17T10:22:16.96Z","cvss":[{"version":"4.0","score":1,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:N/AU:Y/R:A/V:C/RE:L/U:Green","level":"low","assessor":"secondary"},{"version":"3.1","score":2.5,"vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N","level":"low","assessor":"primary"}],"cwes":["CWE-208"],"updated_at":"2026-11-02T14:12:05.52517Z"}],"osv":[{"id":"CVE-2026-23901","description":"Observable Timing Discrepancy vulnerability in Apache Shiro.\n\nThis issue affects Apache Shiro: from 1.*, 2.* before 2.0.7.\n\nUsers are recommended to upgrade to version 2.0.7 or later, which fixes the issue.\n\nPrior to Shiro 2.0.7, code paths for non-existent vs. existing users are different enough,\nthat a brute-force attack may be able to tell, by timing the requests only, determine if\nthe request failed because of a non-existent user vs. wrong password.\n\nThe most likely attack vector is a local attack only.\nShiro security model  https://shiro.apache.org/security-model.html#username_enumeration  discusses this as well.\n\nTypically, brute force attack can be mitigated at the infrastructure level.","status":"published","published":"2026-02-10T10:15:59.24Z","modified":"2026-03-13T04:09:37.721434Z","cvss":[{"version":"3.1","score":2.5,"vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N","level":"low"}],"updated_at":"2026-11-02T15:44:59.079784Z"},{"id":"DEBIAN-CVE-2026-23901","description":"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.","status":"published","published":"2026-02-10T10:15:59.24Z","modified":"2026-10-05T04:00:11.224268898Z","cvss":[{"version":"3.1","score":2.5,"vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N","level":"low"}],"updated_at":"2026-11-02T15:45:53.516942Z"},{"id":"GHSA-c4qc-4q9p-m9q9","title":"Apache Shiro Affected by an Observable Timing Discrepancy Vulnerability","description":"Observable Timing Discrepancy vulnerability in Apache Shiro.\n\nThis issue affects Apache Shiro: from 1.*, 2.* before 2.0.7.\n\nUsers are recommended to upgrade to version 2.0.7 or later, which fixes the issue.\n\nPrior to Shiro 2.0.7, code paths for non-existent vs. existing users are different enough,\nthat a brute-force attack may be able to tell, by timing the requests only, determine if\nthe request failed because of a non-existent user vs. wrong password.\n\nThe most likely attack vector is a local attack only.\nShiro security model  https://shiro.apache.org/security-model.html#username_enumeration  discusses this as well.\n\nTypically, brute force attack can be mitigated at the infrastructure level.","status":"published","published":"2026-02-10T12:30:28Z","modified":"2026-09-10T03:50:59.454968303Z","cvss":[{"version":"4.0","score":1,"vector":"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","level":"low"}],"cwes":["CWE-208"],"updated_at":"2026-11-02T15:46:44.571161Z"},{"id":"UBUNTU-CVE-2026-23901","description":"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.","status":"published","published":"2026-02-10T10:15:00Z","modified":"2026-10-17T12:59:55.693579022Z","cvss":[{"version":"4.0","score":1,"vector":"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","level":"low"},{"version":"3.1","score":2.5,"vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N","level":"low"}],"updated_at":"2026-11-02T16:56:04.456047Z"}]}}