{"id":"CVE-2021-30639","aliases":["BIT-tomcat-2021-30639","GHSA-44qp-qhfv-c7f6"],"url":"https://o3.security/vulnerability/CVE-2021-30639","summary":"Improper Handling of Exceptional Conditions in Apache Tomcat","details":"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.","published":"2021-07-12T15:15:08.333Z","modified":"2026-07-08T05:59:11.808504669Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Maven","name":"org.apache.tomcat:tomcat","fixedVersion":"10.0.5"},{"ecosystem":"Maven","name":"org.apache.tomcat:tomcat","fixedVersion":"9.0.45"},{"ecosystem":"Maven","name":"org.apache.tomcat:tomcat","fixedVersion":"8.5.65"}],"fix":null,"references":[{"type":"WEB","url":"https://lists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf%40%3Cdev.tomcat.apache.org%3E"},{"type":"WEB","url":"https://lists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf%40%3Cusers.tomcat.apache.org%3E"},{"type":"ADVISORY","url":"https://kc.mcafee.com/corporate/index?page=content&id=SB10366"},{"type":"ADVISORY","url":"https://lists.apache.org/thread.html/rd84fae1f474597bdf358f5bdc0a5c453c507bd527b83e8be6b5ea3f4%40%3Cannounce.tomcat.apache.org%3E"},{"type":"ADVISORY","url":"https://security.gentoo.org/glsa/202208-34"},{"type":"ADVISORY","url":"https://security.netapp.com/advisory/ntap-20210827-0007/"},{"type":"FIX","url":"https://www.oracle.com/security-alerts/cpujan2022.html"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-08T05:59:11.808504669Z"}}