{"id":"CVE-2015-1853","aliases":["DEBIAN-CVE-2015-1853","DLA-193-1","DSA-3222-1","EUVD-2015-1962","GHSA-gf8j-j7q8-vhh5","MGASA-2015-0163","RHSA-2015:2241","UBUNTU-CVE-2015-1853"],"status":"published","title":"chrony before 1.31.1 does not properly protect state variables in authenticated symmetric NTP...","description":"chrony before 1.31.1 does not properly protect state variables in authenticated symmetric NTP associations, which allows remote attackers with knowledge of NTP peering to cause a denial of service (inability to synchronize) via random timestamps in crafted NTP data packets.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-09","score":0.01696,"percentile":0.77314,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"published":"2015-04-12T00:00:00Z","modified":"2026-09-09T07:00:22Z","fixes":[{"ecosystem":"Debian:12","package":"chrony","fixed_in":["1.30-2"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"chrony","fixed_in":["1.30-2"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"chrony","fixed_in":["1.30-2"],"sources":["osv"]},{"ecosystem":"Ubuntu:14.04:LTS","package":"chrony","fixed_in":["1.29-1ubuntu0.1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Debian:12","package":"chrony","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.30-2"}]}]},{"source":"osv","ecosystem":"Debian:13","package":"chrony","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.30-2"}]}]},{"source":"osv","ecosystem":"Debian:14","package":"chrony","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.30-2"}]}]},{"source":"osv","ecosystem":"Debian:6.0","package":"chrony","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.24-3+squeeze2"}]}],"versions":["1.24-3","1.24-3+squeeze1"],"bundled":3},{"source":"osv","ecosystem":"Debian:7","package":"chrony","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.24-3.1+deb7u3"}]}],"versions":["1.24-3.1+deb7u1","1.24-3.1+deb7u2"],"bundled":3},{"source":"osv","ecosystem":"Mageia:4","package":"chrony","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.29.1-1.1.mga4"}]}],"bundled":3},{"source":"osv","ecosystem":"Red Hat:enterprise_linux:7::client","package":"chrony","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0:2.1.1-1.el7"}]}],"bundled":3},{"source":"osv","ecosystem":"Red Hat:enterprise_linux:7::client","package":"chrony-debuginfo","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0:2.1.1-1.el7"}]}],"bundled":3},{"source":"osv","ecosystem":"Red Hat:enterprise_linux:7::computenode","package":"chrony","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0:2.1.1-1.el7"}]}],"bundled":3},{"source":"osv","ecosystem":"Red Hat:enterprise_linux:7::computenode","package":"chrony-debuginfo","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0:2.1.1-1.el7"}]}],"bundled":3},{"source":"osv","ecosystem":"Red Hat:enterprise_linux:7::server","package":"chrony","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0:2.1.1-1.el7"}]}],"bundled":3},{"source":"osv","ecosystem":"Red Hat:enterprise_linux:7::server","package":"chrony-debuginfo","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0:2.1.1-1.el7"}]}],"bundled":3},{"source":"osv","ecosystem":"Red Hat:enterprise_linux:7::workstation","package":"chrony","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0:2.1.1-1.el7"}]}],"bundled":3},{"source":"osv","ecosystem":"Red Hat:enterprise_linux:7::workstation","package":"chrony-debuginfo","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0:2.1.1-1.el7"}]}],"bundled":3},{"source":"osv","ecosystem":"Ubuntu:14.04:LTS","package":"chrony","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.29-1ubuntu0.1"}]}],"versions":["1.26-4","1.29-1"]}],"products":[{"vendor":"chrony","product":"chrony"},{"vendor":"tuxfamily","product":"chrony"}],"references":[{"url":"https://security.gentoo.org/glsa/201507-01","tags":["x_refsource_MISC","x_transferred","Third Party Advisory","advisory"]},{"url":"http://chrony.tuxfamily.org/News.html","tags":["x_refsource_MISC","x_transferred","Release Notes","Vendor Advisory","advisory","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2015-1853","tags":["advisory"]},{"url":"https://access.redhat.com/errata/RHSA-2015:2241","tags":["advisory"]},{"url":"https://access.redhat.com/security/cve/CVE-2015-1853","tags":["report"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1209572","tags":["report"]},{"url":"https://github.com/advisories/GHSA-gf8j-j7q8-vhh5"},{"url":"https://security-tracker.debian.org/tracker/CVE-2015-1853","tags":["advisory"]},{"url":"https://advisories.mageia.org/MGASA-2015-0163.html","tags":["advisory"]},{"url":"https://bugs.mageia.org/show_bug.cgi?id=15647","tags":["report"]},{"url":"https://www.debian.org/security/2015/dsa-3222","tags":["web"]},{"url":"https://access.redhat.com/security/updates/classification/#moderate","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1117882","tags":["report"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1169353","tags":["report"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1206504","tags":["report"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1209568","tags":["report"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1209631","tags":["report"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1209632","tags":["report"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1211600","tags":["report"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1219492","tags":["report"]},{"url":"https://security.access.redhat.com/data/csaf/v2/advisories/2015/rhsa-2015_2241.json","tags":["advisory"]},{"url":"https://access.redhat.com/security/cve/CVE-2015-1821","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2015-1821","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2015-1821","tags":["advisory"]},{"url":"https://access.redhat.com/security/cve/CVE-2015-1822","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2015-1822","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2015-1822","tags":["advisory"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2015-1853","tags":["advisory","report"]},{"url":"https://ubuntu.com/security/CVE-2015-1853","tags":["report"]},{"url":"http://www.openwall.com/lists/oss-security/2015/04/07/10","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2015-1853","description":"chrony before 1.31.1 does not properly protect state variables in authenticated symmetric NTP associations, which allows remote attackers with knowledge of NTP peering to cause a denial of service (inability to synchronize) via random timestamps in crafted NTP data packets.","status":"published","published":"2019-12-09T18:53:22Z","modified":"2024-08-06T04:54:16.335Z","updated_at":"2026-11-02T14:35:43.698357Z"}],"euvd":[{"id":"EUVD-2015-1962","description":"chrony before 1.31.1 does not properly protect state variables in authenticated symmetric NTP associations, which allows remote attackers with knowledge of NTP peering to cause a denial of service (inability to synchronize) via random timestamps in crafted NTP data packets.","status":"published","published":"2019-12-09T18:53:22Z","modified":"2024-08-06T04:54:16Z","updated_at":"2026-11-03T02:22:14.212001Z"}],"ghsa":[{"id":"GHSA-gf8j-j7q8-vhh5","title":"chrony before 1.31.1 does not properly protect state variables in authenticated symmetric NTP...","description":"chrony before 1.31.1 does not properly protect state variables in authenticated symmetric NTP associations, which allows remote attackers with knowledge of NTP peering to cause a denial of service (inability to synchronize) via random timestamps in crafted NTP data packets.","status":"published","published":"2022-05-24T17:02:53Z","modified":"2023-02-02T21:34:01Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T14:52:47.993176Z"}],"nvd":[{"id":"CVE-2015-1853","description":"chrony before 1.31.1 does not properly protect state variables in authenticated symmetric NTP associations, which allows remote attackers with knowledge of NTP peering to cause a denial of service (inability to synchronize) via random timestamps in crafted NTP data packets.","status":"published","published":"2019-12-09T19:15:14.15Z","modified":"2026-06-17T00:23:07.07Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"primary"},{"version":"2.0","score":4,"vector":"AV:N/AC:L/Au:S/C:N/I:N/A:P","level":"medium","assessor":"primary"}],"updated_at":"2026-11-02T14:03:19.73542Z"}],"osv":[{"id":"CVE-2015-1853","description":"chrony before 1.31.1 does not properly protect state variables in authenticated symmetric NTP associations, which allows remote attackers with knowledge of NTP peering to cause a denial of service (inability to synchronize) via random timestamps in crafted NTP data packets.","status":"published","published":"2019-12-09T19:15:14Z","modified":"2026-04-16T06:24:22.452076303Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T15:44:00.594921Z"},{"id":"DEBIAN-CVE-2015-1853","description":"chrony before 1.31.1 does not properly protect state variables in authenticated symmetric NTP associations, which allows remote attackers with knowledge of NTP peering to cause a denial of service (inability to synchronize) via random timestamps in crafted NTP data packets.","status":"published","published":"2019-12-09T19:15:14.15Z","modified":"2026-09-09T07:00:22.058659393Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T15:45:26.752992Z"},{"id":"UBUNTU-CVE-2015-1853","description":"chrony before 1.31.1 does not properly protect state variables in authenticated symmetric NTP associations, which allows remote attackers with knowledge of NTP peering to cause a denial of service (inability to synchronize) via random timestamps in crafted NTP data packets.","status":"published","published":"2019-12-09T19:15:00Z","modified":"2025-09-08T16:43:20Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T15:54:10.045446Z"},{"id":"DLA-193-1","title":"chrony - security update","status":"published","published":"2015-04-12T00:00:00Z","modified":"2026-03-09T01:21:20.727005Z","updated_at":"2026-11-02T15:46:10.227108Z"},{"id":"DSA-3222-1","title":"chrony - security update","status":"published","published":"2015-04-12T00:00:00Z","modified":"2026-03-09T01:18:47.627488Z","updated_at":"2026-11-02T15:46:15.843838Z"},{"id":"MGASA-2015-0163","title":"Updated chrony packages fix security vulnerabilities","description":"Updated chrony package fixes security vulnerabilities:\n\nUsing particular address/subnet pairs when configuring access control would\ncause an invalid memory write. This could allow attackers to cause a denial\nof service (crash) or execute arbitrary code (CVE-2015-1821).\n\nWhen allocating memory to save unacknowledged replies to authenticated\ncommand requests, a pointer would be left uninitialized, which could trigger\nan invalid memory write. This could allow attackers to cause a denial of\nservice (crash) or execute arbitrary code (CVE-2015-1822).\n\nWhen peering with other NTP hosts using authenticated symmetric association,\nthe internal state variables would be updated before the MAC of the NTP\nmessages was validated. This could allow a remote attacker to cause a denial\nof service by impeding synchronization between NTP peers (CVE-2015-1853).\n","status":"published","published":"2015-04-23T21:14:25Z","modified":"2026-04-16T06:24:47.505136031Z","updated_at":"2026-11-02T15:49:39.488462Z"},{"id":"RHSA-2015:2241","title":"Red Hat Security Advisory: chrony security, bug fix, and enhancement update","status":"published","published":"2024-09-15T22:35:28Z","modified":"2026-06-27T10:03:27Z","updated_at":"2026-11-02T15:53:03.182161Z"}]}}