Improper Handling of Exceptional Conditions in Apache Tomcat
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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.apache.tomcat:tomcat | >= 10.0.3, < 10.0.5, >= 9.0.0, < 9.0.45, < 8.5.65 | 10.0.5, 9.0.45, 8.5.65 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2021-30639
- https://kc.mcafee.com/corporate/index?page=content&id=SB10366
- 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://lists.apache.org/thread.html/rd84fae1f474597bdf358f5bdc0a5c453c507bd527b83e8be6b5ea3f4%40%3Cannounce.tomcat.apache.org%3E
- https://security.gentoo.org/glsa/202208-34
- https://security.netapp.com/advisory/ntap-20210827-0007
- https://www.oracle.com/security-alerts/cpujan2022.html
- 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- Platform
- Java / Kotlin (Maven)
- Package
org.apache.tomcat:tomcat- Disclosed
- 13.08.2021
- Updated
- 11.10.2026 11:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-44qp-qhfv-c7f6 - CC BY 4.0
Vulnerability history: org.apache.tomcat:tomcat
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 162
- First → latest
- 12.2018 08.2026
- Without a fix
- 20
- Exploited in attacks
- 1
Severity breakdown
- Critical 8
- High 40
- Medium 102
- Low 12
Disclosures per year
- 2018: 1
- 2019: 1
- 2020: 2
- 2021: 5
- 2022: 125
- 2023: 3
- 2024: 2
- 2025: 4
- 2026: 19
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