Is CVE-2021-30639 being actively exploited?

CVE-2021-30639 is not currently listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

What is the CVSS score for CVE-2021-30639?

CVE-2021-30639 has a CVSS 3.1 base score of 7.5 (HIGH).

CVE-2021-30639

HIGH · CVSS 7.5EPSS 6.9%EU EUVD

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.

Key facts

CVSS score: 7.5 (v3.1)
Severity: HIGH
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-755
EPSS score: 6.9% (94th percentile)
In CISA KEV: No
In EU EUVD: Yes (EUVD-2021-1554)
Published: July 12, 2021
NVD last modified: June 17, 2026
Status: Modified

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2021-1554 in the EU Vulnerability Database. Last updated in EUVD on August 3, 2024.

View on the EU Vulnerability Database

Affected products

apache / tomcat
apache / tomcat
apache / tomcat
apache / tomcat
mcafee / epolicy orchestrator
mcafee / epolicy orchestrator
mcafee / epolicy orchestrator
mcafee / epolicy orchestrator
mcafee / epolicy orchestrator
mcafee / epolicy orchestrator
mcafee / epolicy orchestrator
mcafee / epolicy orchestrator
mcafee / epolicy orchestrator
mcafee / epolicy orchestrator
mcafee / epolicy orchestrator
mcafee / epolicy orchestrator
oracle / big data spatial and graph

Certified products that may be affected

2 FIPS 140 or Common Criteria certified products, from automated matching by sec-certs.org.

McAfee Application Control v5.0, Change Control v5.0, and Integrity Monitor v5.0 with McAfee Agent v4.5 and ePolicy Orchestrator v4.5 - McAfee, Inc. - Common Criteria 383-4-153 - archived
McAfee VirusScan Enterprise v8.5i and McAfee ePolicy Orchestrator v3.6 - McAfee, Inc. - Common Criteria CCEVS-VR-0047-2007 - archived

References

https://kc.mcafee.com/corporate/index?page=content&id=SB10366(Third Party Advisory)
https://lists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf%40%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf%40%3Cusers.tomcat.apache.org%3E
https://lists.apache.org/thread.html/rd84fae1f474597bdf358f5bdc0a5c453c507bd527b83e8be6b5ea3f4%40%3Cannounce.tomcat.apache.org%3E(Mailing List, Vendor Advisory)
https://security.gentoo.org/glsa/202208-34(Third Party Advisory)
https://security.netapp.com/advisory/ntap-20210827-0007/(Third Party Advisory)
https://www.oracle.com/security-alerts/cpujan2022.html(Patch, Third Party Advisory)

Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS

Query CVEs from your AI assistant

The CVE/NVD Explorer brain answers CVE questions directly inside Claude, ChatGPT, or any MCP assistant — always up to date, no setup. Add it once and stop pasting advisories into chat.

Add the CVE brain