{"id":"CVE-2021-30639","aliases":["BIT-tomcat-2021-30639","CLSA-2025-1748282295","EUVD-2021-1554","GHSA-44qp-qhfv-c7f6","UBUNTU-CVE-2021-30639"],"status":"published","title":"DoS after non-blocking IO error","description":"A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service. An error introduced as part of a change to improve error handling during non-blocking I/O meant that the error flag associated with the Request object was not reset between requests. This meant that once a non-blocking I/O error occurred, all future requests handled by that request object would fail. Users were able to trigger non-blocking I/O errors, e.g. by dropping a connection, thereby creating the possibility of triggering a DoS. Applications that do not use non-blocking I/O are not exposed to this vulnerability. This issue affects Apache Tomcat 10.0.3 to 10.0.4; 9.0.44; 8.5.64.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-11","score":0.06889,"percentile":0.94152,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-755"],"published":"2021-07-12T14:55:12Z","modified":"2026-10-24T10:30:40Z","fixes":[{"ecosystem":"Maven","package":"org.apache.tomcat:tomcat","fixed_in":["10.0.5","9.0.45","8.5.65"],"sources":["ghsa","osv"]},{"ecosystem":"Bitnami","package":"tomcat","fixed_in":["8.5.65","9.0.45","10.0.4","10.0.5"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"Maven","package":"org.apache.tomcat:tomcat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"10.0.3"},{"fixed":"10.0.5"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.apache.tomcat:tomcat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"9.0.0"},{"fixed":"9.0.45"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.apache.tomcat:tomcat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.5.65"}]}]},{"source":"osv","ecosystem":"Bitnami","package":"tomcat","ranges":[{"type":"SEMVER","events":[{"introduced":"8.5.64"},{"fixed":"8.5.65"},{"introduced":"9.0.44"},{"fixed":"9.0.45"},{"introduced":"10.0.3"},{"fixed":"10.0.4"},{"introduced":"10.0.4"},{"fixed":"10.0.5"}]}]},{"source":"osv","ecosystem":"TuxCare:Ubuntu:18.04","package":"libtomcat8-embed-java","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.5.100-1ubuntu1~18.04.1+tuxcare.els1"}]}],"bundled":34},{"source":"osv","ecosystem":"TuxCare:Ubuntu:18.04","package":"libtomcat8-java","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.5.100-1ubuntu1~18.04.1+tuxcare.els1"}]}],"bundled":34},{"source":"osv","ecosystem":"TuxCare:Ubuntu:18.04","package":"tomcat8","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.5.100-1ubuntu1~18.04.1+tuxcare.els1"}]}],"bundled":34},{"source":"osv","ecosystem":"TuxCare:Ubuntu:18.04","package":"tomcat8-admin","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.5.100-1ubuntu1~18.04.1+tuxcare.els1"}]}],"bundled":34},{"source":"osv","ecosystem":"TuxCare:Ubuntu:18.04","package":"tomcat8-common","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.5.100-1ubuntu1~18.04.1+tuxcare.els1"}]}],"bundled":34},{"source":"osv","ecosystem":"TuxCare:Ubuntu:18.04","package":"tomcat8-docs","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.5.100-1ubuntu1~18.04.1+tuxcare.els1"}]}],"bundled":34},{"source":"osv","ecosystem":"TuxCare:Ubuntu:18.04","package":"tomcat8-examples","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.5.100-1ubuntu1~18.04.1+tuxcare.els1"}]}],"bundled":34},{"source":"osv","ecosystem":"TuxCare:Ubuntu:18.04","package":"tomcat8-user","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.5.100-1ubuntu1~18.04.1+tuxcare.els1"}]}],"bundled":34},{"source":"osv","ecosystem":"Maven","package":"org.apache.tomcat:tomcat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"10.0.3"},{"fixed":"10.0.5"}]}],"versions":["10.0.4"]},{"source":"osv","ecosystem":"Maven","package":"org.apache.tomcat:tomcat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"9.0.0"},{"fixed":"9.0.45"}]}],"versions":["9.0.1","9.0.10","9.0.11","9.0.12","9.0.13","9.0.14","9.0.16","9.0.17","9.0.19","9.0.2","9.0.20","9.0.21","9.0.22","9.0.24","9.0.26","9.0.27","9.0.29","9.0.30","9.0.31","9.0.33","9.0.34","9.0.35","9.0.36","9.0.37","9.0.38","9.0.39","9.0.4","9.0.40","9.0.41","9.0.43","9.0.44","9.0.5","9.0.6","9.0.7","9.0.8"]},{"source":"osv","ecosystem":"Maven","package":"org.apache.tomcat:tomcat","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.5.65"}]}],"versions":["7.0.100","7.0.103","7.0.104","7.0.105","7.0.106","7.0.107","7.0.108","7.0.109","7.0.35","7.0.37","7.0.39","7.0.40","7.0.41","7.0.42","7.0.47","7.0.50","7.0.52","7.0.53","7.0.54","7.0.55","7.0.56","7.0.57","7.0.59","7.0.61","7.0.62","7.0.63","7.0.64","7.0.65","7.0.67","7.0.68","7.0.69","7.0.70","7.0.72","7.0.73","7.0.75","7.0.76","7.0.77","7.0.78","7.0.79","7.0.81","7.0.82","7.0.84","7.0.85","7.0.86","7.0.88","7.0.90","7.0.91","7.0.92","7.0.93","7.0.94","7.0.96","7.0.99","8.0.0-RC1","8.0.0-RC10","8.0.0-RC3","8.0.0-RC5","8.0.1","8.0.11","8.0.12","8.0.14","8.0.15","8.0.17","8.0.18","8.0.20","8.0.21","8.0.22","8.0.23","8.0.24","8.0.26","8.0.27","8.0.28","8.0.29","8.0.3","8.0.30","8.0.32","8.0.33","8.0.35","8.0.36","8.0.37","8.0.38","8.0.39","8.0.41","8.0.42","8.0.43","8.0.44","8.0.45","8.0.46","8.0.47","8.0.48","8.0.49","8.0.5","8.0.50","8.0.51","8.0.52","8.0.53","8.0.8","8.0.9","8.5.0","8.5.11","8.5.12","8.5.13","8.5.14","8.5.15","8.5.16","8.5.19","8.5.2","8.5.20","8.5.21","8.5.23","8.5.24","8.5.27","8.5.28","8.5.29","8.5.3","8.5.30","8.5.31","8.5.32","8.5.33","8.5.34","8.5.35","8.5.37","8.5.38","8.5.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software foundation","product":"apache tomcat"},{"vendor":"mcafee","product":"epolicy_orchestrator"},{"vendor":"oracle","product":"big_data_spatial_and_graph"}],"references":[{"url":"https://lists.apache.org/thread.html/rd84fae1f474597bdf358f5bdc0a5c453c507bd527b83e8be6b5ea3f4%40%3Cannounce.tomcat.apache.org%3E","tags":["x_refsource_MISC","x_transferred","Mailing List","Vendor Advisory","advisory","web","report"]},{"url":"https://lists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf%40%3Cusers.tomcat.apache.org%3E","tags":["mailing-list","x_refsource_MLIST","x_transferred","web"]},{"url":"https://lists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf%40%3Cdev.tomcat.apache.org%3E","tags":["mailing-list","x_refsource_MLIST","x_transferred","web"]},{"url":"https://security.netapp.com/advisory/ntap-20210827-0007/","tags":["x_refsource_CONFIRM","x_transferred","Third Party Advisory","advisory"]},{"url":"https://kc.mcafee.com/corporate/index?page=content\u0026id=SB10366","tags":["x_refsource_CONFIRM","x_transferred","Third Party Advisory","advisory","web"]},{"url":"https://www.oracle.com/security-alerts/cpujan2022.html","tags":["x_refsource_MISC","x_transferred","Patch","Third Party Advisory","advisory","fix","web"]},{"url":"https://security.gentoo.org/glsa/202208-34","tags":["vendor-advisory","x_refsource_GENTOO","x_transferred","Third Party Advisory","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-30639","tags":["web","advisory"]},{"url":"https://lists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf@%3Cdev.tomcat.apache.org%3E","tags":["web","report"]},{"url":"https://lists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf@%3Cusers.tomcat.apache.org%3E","tags":["web","report"]},{"url":"https://github.com/advisories/GHSA-44qp-qhfv-c7f6"},{"url":"https://errata.cloudlinux.com/ubuntu18-els/CLSA-2025-1748282295.html","tags":["advisory"]},{"url":"https://security.netapp.com/advisory/ntap-20210827-0007","tags":["web"]},{"url":"https://ubuntu.com/security/CVE-2021-30639","tags":["report"]},{"url":"https://bz.apache.org/bugzilla/show_bug.cgi?id=65203","tags":["report"]},{"url":"https://github.com/apache/tomcat/commit/8ece47c4a9fb9349e8862c84358a4dd23c643a24","tags":["report"]},{"url":"https://github.com/apache/tomcat/commit/411caf29ac1c16e6ac291b6e5543b2371dbd25e2","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2021-30639","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2021-30639","title":"DoS after non-blocking IO error","description":"A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service. An error introduced as part of a change to improve error handling during non-blocking I/O meant that the error flag associated with the Request object was not reset between requests. This meant that once a non-blocking I/O error occurred, all future requests handled by that request object would fail. Users were able to trigger non-blocking I/O errors, e.g. by dropping a connection, thereby creating the possibility of triggering a DoS. Applications that do not use non-blocking I/O are not exposed to this vulnerability. This issue affects Apache Tomcat 10.0.3 to 10.0.4; 9.0.44; 8.5.64.","status":"published","published":"2021-07-12T14:55:12Z","modified":"2024-08-03T22:40:31.655Z","updated_at":"2026-11-02T14:33:02.20241Z"}],"euvd":[{"id":"EUVD-2021-1554","description":"A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service. An error introduced as part of a change to improve error handling during non-blocking I/O meant that the error flag associated with the Request object was not reset between requests. This meant that once a non-blocking I/O error occurred, all future requests handled by that request object would fail. Users were able to trigger non-blocking I/O errors, e.g. by dropping a connection, thereby creating the possibility of triggering a DoS. Applications that do not use non-blocking I/O are not exposed to this vulnerability. This issue affects Apache Tomcat 10.0.3 to 10.0.4; 9.0.44; 8.5.64.","status":"published","published":"2021-07-12T14:55:12Z","modified":"2024-08-03T22:40:31Z","updated_at":"2026-11-03T03:24:41.467382Z"}],"ghsa":[{"id":"GHSA-44qp-qhfv-c7f6","title":"Improper Handling of Exceptional Conditions in Apache Tomcat","description":"A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service. An error introduced as part of a change to improve error handling during non-blocking I/O meant that the error flag associated with the Request object was not reset between requests. This meant that once a non-blocking I/O error occurred, all future requests handled by that request object would fail. Users were able to trigger non-blocking I/O errors, e.g. by dropping a connection, thereby creating the possibility of triggering a DoS. Applications that do not use non-blocking I/O are not exposed to this vulnerability. This issue affects Apache Tomcat 10.0.3 to 10.0.4; 9.0.44; 8.5.64.","status":"published","published":"2021-08-13T15:21:02Z","modified":"2023-02-03T05:04:43Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-755"],"updated_at":"2026-11-02T14:36:41.967989Z"}],"nvd":[{"id":"CVE-2021-30639","description":"A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service. An error introduced as part of a change to improve error handling during non-blocking I/O meant that the error flag associated with the Request object was not reset between requests. This meant that once a non-blocking I/O error occurred, all future requests handled by that request object would fail. Users were able to trigger non-blocking I/O errors, e.g. by dropping a connection, thereby creating the possibility of triggering a DoS. Applications that do not use non-blocking I/O are not exposed to this vulnerability. This issue affects Apache Tomcat 10.0.3 to 10.0.4; 9.0.44; 8.5.64.","status":"published","published":"2021-07-12T15:15:08.333Z","modified":"2026-06-17T03:50:36.64Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary"},{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:N/I:N/A:P","level":"medium","assessor":"primary"}],"cwes":["CWE-755"],"updated_at":"2026-11-02T14:06:55.747384Z"}],"osv":[{"id":"CVE-2021-30639","description":"A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service. An error introduced as part of a change to improve error handling during non-blocking I/O meant that the error flag associated with the Request object was not reset between requests. This meant that once a non-blocking I/O error occurred, all future requests handled by that request object would fail. Users were able to trigger non-blocking I/O errors, e.g. by dropping a connection, thereby creating the possibility of triggering a DoS. Applications that do not use non-blocking I/O are not exposed to this vulnerability. This issue affects Apache Tomcat 10.0.3 to 10.0.4; 9.0.44; 8.5.64.","status":"published","published":"2021-07-12T15:15:08.333Z","modified":"2026-10-24T10:30:40.136384269Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:44:19.483607Z"},{"id":"GHSA-44qp-qhfv-c7f6","title":"Improper Handling of Exceptional Conditions in Apache Tomcat","description":"A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service. An error introduced as part of a change to improve error handling during non-blocking I/O meant that the error flag associated with the Request object was not reset between requests. This meant that once a non-blocking I/O error occurred, all future requests handled by that request object would fail. Users were able to trigger non-blocking I/O errors, e.g. by dropping a connection, thereby creating the possibility of triggering a DoS. Applications that do not use non-blocking I/O are not exposed to this vulnerability. This issue affects Apache Tomcat 10.0.3 to 10.0.4; 9.0.44; 8.5.64.","status":"published","published":"2021-08-13T15:21:02Z","modified":"2024-02-19T05:32:15.919393Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-755"],"updated_at":"2026-11-02T15:46:36.434231Z"},{"id":"UBUNTU-CVE-2021-30639","description":"A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service. An error introduced as part of a change to improve error handling during non-blocking I/O meant that the error flag associated with the Request object was not reset between requests. This meant that once a non-blocking I/O error occurred, all future requests handled by that request object would fail. Users were able to trigger non-blocking I/O errors, e.g. by dropping a connection, thereby creating the possibility of triggering a DoS. Applications that do not use non-blocking I/O are not exposed to this vulnerability. This issue affects Apache Tomcat 10.0.3 to 10.0.4; 9.0.44; 8.5.64.","status":"withdrawn","published":"2021-07-12T15:15:00Z","modified":"2025-07-14T06:45:36.726472Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:54:27.332852Z"},{"id":"BIT-tomcat-2021-30639","title":"DoS after non-blocking IO error","description":"A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service. An error introduced as part of a change to improve error handling during non-blocking I/O meant that the error flag associated with the Request object was not reset between requests. This meant that once a non-blocking I/O error occurred, all future requests handled by that request object would fail. Users were able to trigger non-blocking I/O errors, e.g. by dropping a connection, thereby creating the possibility of triggering a DoS. Applications that do not use non-blocking I/O are not exposed to this vulnerability. This issue affects Apache Tomcat 10.0.3 to 10.0.4; 9.0.44; 8.5.64.","status":"published","published":"2024-03-06T11:10:12.195Z","modified":"2026-09-08T08:48:20.858738938Z","updated_at":"2026-11-02T15:28:36.104787Z"},{"id":"CLSA-2025-1748282295","title":"Fix of 34 CVEs","description":"   * SECURITY UPDATE: Misc vulnerability fixes\n     - CVE-2019-12418, CVE-2019-17563, CVE-2020-1935,\n       CVE-2020-11996, CVE-2020-13934, CVE-2020-13935,\n       CVE-2020-13943, CVE-2020-17527, CVE-2021-24122,\n       CVE-2021-30639, CVE-2021-30640, CVE-2021-33037,\n       CVE-2021-42340, CVE-2021-43980, CVE-2022-25762,\n       CVE-2022-34305, CVE-2022-45143, CVE-2023-24998,\n       CVE-2023-28709, CVE-2023-34981, CVE-2023-42794,\n       CVE-2024-21733\n   * Update to 8.5.100\n     - debian/rules,\n       debian/libtomcat8-java.poms,\n       debian/maven.rules,\n       debian/tomcat8-common.links,\n       debian/patches/0018-fix-manager-webapp.patch,\n       debian/patches/0019-add-distribution-to-error-page.patch,\n       debian/patches/0021-dont-test-unsupported-ciphers.patch,\n       debian/patches/0101-skipping-tests-incompatible-with-firewall.patch:\n       updated\n     - debian/patches/0002-do-not-load-AJP13-connector-by-default.patch,\n       debian/patches/0026-easymock4-compatibility.patch:\n       removed as they were applied in upstream\n     - CVE-2019-0221.patch, CVE-2019-10072-1.patch,\n       CVE-2019-10072-2.patch, CVE-2022-42252.patch,\n       CVE-2020-1938.patch, CVE-2021-25122.patch,\n       CVE-2021-41079.patch, CVE-2022-29885.patch,\n       CVE-2020-9484.patch, CVE-2021-25329-pre1.patch,\n       CVE-2021-25329.patch, CVE-2022-23181.patch,\n       CVE-2023-44487.patch, CVE-2023-46589-pre1.patch,\n       CVE-2023-46589-pre2.patch, CVE-2023-46589-pre3.patch,\n       CVE-2023-46589-pre4.patch, CVE-2023-46589.patch:\n       removed because these CVEs were fixed in upstream\n   * Internal tests\n     - debian/test_certs/*: updated from upstream branch 9.0.x, as the\n       8.0.x certs were expired","status":"published","published":"2025-05-27T13:45:18Z","modified":"2026-06-04T10:03:30.412984079Z","updated_at":"2026-11-02T15:43:41.66212Z"}]}}