{"id":"CVE-2021-34431","aliases":["DEBIAN-CVE-2021-34431","EUVD-2021-21087","GHSA-j546-3m5x-fx7p","UBUNTU-CVE-2021-34431","USN-6492-1"],"status":"published","title":"In Eclipse Mosquitto version 1.6 to 2.0.10, if an authenticated client that had connected with...","description":"In Eclipse Mosquitto version 1.6 to 2.0.10, if an authenticated client that had connected with MQTT v5 sent a crafted CONNECT message to the broker a memory leak would occur, which could be used to provide a DoS attack against the broker.","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":"2026-11-12","score":0.01113,"percentile":0.66459,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-401"],"published":"2021-07-22T13:45:13Z","modified":"2026-10-24T10:30:43Z","fixes":[{"ecosystem":"Debian:12","package":"mosquitto","fixed_in":["2.0.11-1"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"mosquitto","fixed_in":["2.0.11-1"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"mosquitto","fixed_in":["2.0.11-1"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:20.04:LTS","package":"mosquitto","fixed_in":["1.6.9-1ubuntu0.1~esm1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Debian:12","package":"mosquitto","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.11-1"}]}]},{"source":"osv","ecosystem":"Debian:13","package":"mosquitto","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.11-1"}]}]},{"source":"osv","ecosystem":"Debian:14","package":"mosquitto","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.11-1"}]}]},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"mosquitto","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.9-1ubuntu0.1~esm1"}]}],"versions":["1.6.6-1","1.6.7-1","1.6.8-1","1.6.8-2","1.6.9-1~build1","1.6.9-1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"mosquitto","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.9-1ubuntu0.1~esm1"}]}],"versions":["1.6.6-1","1.6.7-1","1.6.8-1","1.6.8-2","1.6.9-1~build1","1.6.9-1"],"bundled":6},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"mosquitto","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.11-1ubuntu1.1"}]}],"versions":["2.0.11-1","2.0.11-1build1","2.0.11-1ubuntu1"],"bundled":6}],"products":[{"vendor":"eclipse","product":"mosquitto"},{"vendor":"the eclipse foundation","product":"eclipse mosquitto"}],"references":[{"url":"https://bugs.eclipse.org/bugs/show_bug.cgi?id=573191","tags":["x_refsource_CONFIRM","x_transferred","Mailing List","Vendor Advisory","advisory","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-34431"},{"url":"https://github.com/advisories/GHSA-j546-3m5x-fx7p"},{"url":"https://security-tracker.debian.org/tracker/CVE-2021-34431","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2021-34431","tags":["report"]},{"url":"https://ubuntu.com/security/notices/USN-6492-1","tags":["advisory"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2021-34431","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2021-34434","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2021-41039","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2023-0809","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2023-3592","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2023-28366","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2021-34431","description":"In Eclipse Mosquitto version 1.6 to 2.0.10, if an authenticated client that had connected with MQTT v5 sent a crafted CONNECT message to the broker a memory leak would occur, which could be used to provide a DoS attack against the broker.","status":"published","published":"2021-07-22T13:45:13Z","modified":"2024-08-04T00:12:50.247Z","cwes":["CWE-401"],"updated_at":"2026-11-02T14:33:11.244759Z"}],"euvd":[{"id":"EUVD-2021-21087","description":"In Eclipse Mosquitto version 1.6 to 2.0.10, if an authenticated client that had connected with MQTT v5 sent a crafted CONNECT message to the broker a memory leak would occur, which could be used to provide a DoS attack against the broker.","status":"published","published":"2021-07-22T13:45:13Z","modified":"2024-08-04T00:12:50Z","updated_at":"2026-11-03T03:24:32.445199Z"}],"ghsa":[{"id":"GHSA-j546-3m5x-fx7p","title":"In Eclipse Mosquitto version 1.6 to 2.0.10, if an authenticated client that had connected with...","description":"In Eclipse Mosquitto version 1.6 to 2.0.10, if an authenticated client that had connected with MQTT v5 sent a crafted CONNECT message to the broker a memory leak would occur, which could be used to provide a DoS attack against the broker.","status":"published","published":"2022-05-24T19:09:00Z","modified":"2023-01-30T05:00:58Z","cwes":["CWE-401"],"updated_at":"2026-11-02T14:46:18.635114Z"}],"nvd":[{"id":"CVE-2021-34431","description":"In Eclipse Mosquitto version 1.6 to 2.0.10, if an authenticated client that had connected with MQTT v5 sent a crafted CONNECT message to the broker a memory leak would occur, which could be used to provide a DoS attack against the broker.","status":"published","published":"2021-07-22T14:15:08.05Z","modified":"2026-06-17T03:55:51.327Z","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"}],"cwes":["CWE-401"],"updated_at":"2026-11-02T14:06:56.185362Z"}],"osv":[{"id":"CVE-2021-34431","description":"In Eclipse Mosquitto version 1.6 to 2.0.10, if an authenticated client that had connected with MQTT v5 sent a crafted CONNECT message to the broker a memory leak would occur, which could be used to provide a DoS attack against the broker.","status":"published","published":"2021-07-22T14:15:08.05Z","modified":"2026-10-24T10:30:43.022849533Z","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":"2026-11-02T15:44:20.13324Z"},{"id":"DEBIAN-CVE-2021-34431","description":"In Eclipse Mosquitto version 1.6 to 2.0.10, if an authenticated client that had connected with MQTT v5 sent a crafted CONNECT message to the broker a memory leak would occur, which could be used to provide a DoS attack against the broker.","status":"published","published":"2021-07-22T14:15:08.05Z","modified":"2026-10-23T18:03:49.632174707Z","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":"2026-11-02T15:45:35.233346Z"},{"id":"UBUNTU-CVE-2021-34431","description":"In Eclipse Mosquitto version 1.6 to 2.0.10, if an authenticated client that had connected with MQTT v5 sent a crafted CONNECT message to the broker a memory leak would occur, which could be used to provide a DoS attack against the broker.","status":"published","published":"2021-07-22T14:15:00Z","modified":"2026-04-22T12:55:45.027618Z","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":"2026-11-02T15:54:27.870979Z"},{"id":"USN-6492-1","title":"mosquitto vulnerabilities","description":"Kathrin Kleinhammer discovered that Mosquitto incorrectly handled certain\ninputs. If a user or an automated system were provided with a specially crafted\ninput, a remote attacker could possibly use this issue to cause a denial of\nservice. This issue only affected Ubuntu 20.04 LTS. (CVE-2021-34431)\n\nZhanxiang Song discovered that Mosquitto incorrectly handled certain inputs. If\na user or an automated system were provided with a specially crafted input, a\nremote attacker could possibly use this issue to cause an authorisation bypass.\nThis issue only affected Ubuntu 22.04 LTS and Ubuntu 23.04. (CVE-2021-34434)\n\nZhanxiang Song, Bin Yuan, DeQing Zou, and Hai Jin discovered that Mosquitto\nincorrectly handled certain inputs. If a user or an automated system were\nprovided with a specially crafted input, a remote attacker could possibly use\nthis issue to cause a denial of service. This issue only affected Ubuntu 20.04\nLTS and Ubuntu 22.04 LTS. (CVE-2021-41039)\n\nZhengjie Du discovered that Mosquitto incorrectly handled certain inputs. If a\nuser or an automated system were provided with a specially crafted input file,\na remote attacker could possibly use this issue to cause a denial of service.\n(CVE-2023-0809)\n\nIt was discovered that Mosquitto incorrectly handled certain inputs. If a user\nor an automated system were provided with a specially crafted input, a remote\nattacker could possibly use this issue to cause a denial of service.\n(CVE-2023-3592)\n\nMischa Bachmann discovered that Mosquitto incorrectly handled certain inputs.\nIf a user or an automated system were provided with a specially crafted input,\na remote attacker could possibly use this issue to cause a denial of service.\nThis issue was only fixed in Ubuntu 22.04 LTS and Ubuntu 23.04.\n(CVE-2023-28366)\n","status":"published","published":"2023-11-21T15:23:51Z","modified":"2026-04-22T10:41:36.101799Z","updated_at":"2026-11-02T16:58:17.305935Z"}]}}