{"id":"CVE-2013-6890","aliases":["DEBIAN-CVE-2013-6890","DSA-2826-1","EUVD-2013-6692","GHSA-f4g4-953x-f5pm","MGASA-2014-0080"],"status":"published","title":"denyhosts 2.6 uses an incorrect regular expression when analyzing authentication logs, which...","description":"denyhosts 2.6 uses an incorrect regular expression when analyzing authentication logs, which allows remote attackers to cause a denial of service (incorrect block of IP addresses) via crafted login names.","severity":{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:N/I:N/A:P","level":"medium","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-09","score":0.08896,"percentile":0.95266,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":true,"fix_available":true},"cwes":["CWE-287"],"published":"2013-12-22T00:00:00Z","modified":"2026-06-17T00:01:05Z","exploits":[{"source":"exploitdb","id":"EDB-38909","title":"DenyHosts - 'regex.py' Remote Denial of Service","type":"dos","platform":"linux","date":"2013-12-19","verified":true,"url":"https://www.exploit-db.com/exploits/38909"}],"fixes":[{"ecosystem":"Debian:6.0","package":"denyhosts","fixed_in":["2.6-7+deb6u2"],"sources":["osv"]},{"ecosystem":"Debian:7","package":"denyhosts","fixed_in":["2.6-10+deb7u2"],"sources":["osv"]},{"ecosystem":"Mageia:3","package":"denyhosts","fixed_in":["2.6-4.4.mga3"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Debian:6.0","package":"denyhosts","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.6-7+deb6u2"}]}],"versions":["2.6-7"]},{"source":"osv","ecosystem":"Debian:7","package":"denyhosts","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.6-10+deb7u2"}]}],"versions":["2.6-10","2.6-10+deb7u1"]},{"source":"osv","ecosystem":"Mageia:3","package":"denyhosts","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.6-4.4.mga3"}]}]}],"products":[{"vendor":"debian","product":"debian_linux"},{"vendor":"fedoraproject","product":"fedora"},{"vendor":"phil_schwartz","product":"denyhosts"}],"references":[{"url":"http://secunia.com/advisories/56239","tags":["third-party-advisory","x_refsource_SECUNIA","x_transferred","Vendor Advisory"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1045982","tags":["x_refsource_MISC","x_transferred"]},{"url":"http://seclists.org/oss-sec/2013/q4/535","tags":["mailing-list","x_refsource_MLIST","x_transferred"]},{"url":"http://www.debian.org/security/2013/dsa-2826","tags":["vendor-advisory","x_refsource_DEBIAN","x_transferred","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2013-6890"},{"url":"https://github.com/advisories/GHSA-f4g4-953x-f5pm"},{"url":"https://advisories.mageia.org/MGASA-2014-0080.html","tags":["advisory"]},{"url":"https://bugs.mageia.org/show_bug.cgi?id=12092","tags":["report"]},{"url":"https://lists.debian.org/debian-security-announce/2014/msg00018.html","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2013-6890","description":"denyhosts 2.6 uses an incorrect regular expression when analyzing authentication logs, which allows remote attackers to cause a denial of service (incorrect block of IP addresses) via crafted login names.","status":"published","published":"2013-12-23T22:00:00Z","modified":"2024-08-06T17:53:44.689Z","updated_at":"2026-11-02T14:34:57.499208Z"}],"euvd":[{"id":"EUVD-2013-6692","description":"denyhosts 2.6 uses an incorrect regular expression when analyzing authentication logs, which allows remote attackers to cause a denial of service (incorrect block of IP addresses) via crafted login names.","status":"published","published":"2013-12-23T22:00:00Z","modified":"2024-08-06T17:53:44Z","updated_at":"2026-11-03T01:56:24.812586Z"}],"ghsa":[{"id":"GHSA-f4g4-953x-f5pm","title":"denyhosts 2.6 uses an incorrect regular expression when analyzing authentication logs, which...","description":"denyhosts 2.6 uses an incorrect regular expression when analyzing authentication logs, which allows remote attackers to cause a denial of service (incorrect block of IP addresses) via crafted login names.","status":"published","published":"2022-05-17T04:55:59Z","modified":"2023-01-28T05:02:58Z","cwes":["CWE-287"],"updated_at":"2026-11-02T14:43:52.645209Z"}],"nvd":[{"id":"CVE-2013-6890","description":"denyhosts 2.6 uses an incorrect regular expression when analyzing authentication logs, which allows remote attackers to cause a denial of service (incorrect block of IP addresses) via crafted login names.","status":"published","published":"2013-12-23T22:55:03.05Z","modified":"2026-06-17T00:01:05.543Z","cvss":[{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:N/I:N/A:P","level":"medium","assessor":"primary"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T14:02:44.596064Z"}],"osv":[{"id":"DSA-2826-1","title":"denyhosts - Remote denial of ssh service","status":"published","published":"2013-12-22T00:00:00Z","modified":"2026-03-09T01:20:35.670075Z","updated_at":"2026-11-02T15:46:15.843838Z"},{"id":"MGASA-2014-0080","title":"Updated denyhosts package fixes security vulnerability","description":"Helmut Grohne discovered that denyhosts, a tool preventing SSH brute-force\nattacks, could be used to perform remote denial of service against the SSH\ndaemon. Incorrectly specified regular expressions used to detect brute\nforce attacks in authentication logs could be exploited by a malicious\nuser to forge crafted login names in order to make denyhosts ban arbitrary\nIP addresses (CVE-2013-6890).\n\nThis update also includes a fix for a regression introduced when fixing\nCVE-2013-6890.\n","status":"published","published":"2014-02-17T00:22:31Z","modified":"2026-04-16T06:25:35.994198099Z","updated_at":"2026-11-02T15:49:39.121227Z"}]}}