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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-30639
• https://lists.apache.org/thread.html/rd84fae1f474597bdf358f5bdc0a5c453c507bd527b83e8be6b5ea3f4%40%3Cannounce.tomcat.apache.org%3E
• https://lists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf@%3Cdev.tomcat.apache.org%3E
• https://lists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf@%3Cusers.tomcat.apache.org%3E
• https://security.netapp.com/advisory/ntap-20210827-0007/
• https://kc.mcafee.com/corporate/index?page=content&id=SB10366
• https://www.oracle.com/security-alerts/cpujan2022.html
• https://security.gentoo.org/glsa/202208-34