CVE-2021-30639
HIGHEPSS 93th pctlDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploit Intelligence
High risk: more likely to be exploited than 93% of all known CVEs.
References
Related Vulnerabilities
Other CWE-755 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2017-5638 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2020-7247 | Critical | 9.8 | 99% | KEV | Fix |
| CVE-2023-36933 | High | 7.5 | 72% | - | Fix |
| CVE-2018-0934 | High | 7.5 | 67% | - | Fix |
| CVE-2019-14287 | High | 8.8 | 64% | - | Fix |
| CVE-2019-12815 | Critical | 9.8 | 58% | - | Fix |
Common questions
How do I fix CVE-2021-30639?
Published advisories record a fix for 2 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2021-30639 being actively exploited?
Not that we know of. CVE-2021-30639 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 6.9% is the estimated probability that it will be exploited in the next 30 days. That is higher than 93% of all scored CVEs.
How severe is CVE-2021-30639?
CVE-2021-30639 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2021-30639 affect?
Published advisories record a fix for big data spatial and graph (NVD), epolicy orchestrator (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.