CVE-2021-30639

DoS after non-blocking IO error

At a glance

Severity
Not available
EPSS
EPSS 6.89 % · percentile 94 (2026-10-27)
State
PUBLISHED
Published
Updated
Assigner
apache
NVD status
Modified

Description

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.

Scores

VersionScoreVectorScored by
CVSS 3.1HIGH 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HNVD · nvd@nist.gov (Primary)
CVSS 2.0MEDIUM 5.0AV:N/AC:L/Au:N/C:N/I:N/A:PNVD · nvd@nist.gov (Primary)

Weaknesses (CWE)

Advisories

European references

Affected configurations (NVD CPE)

Affected products

ProductVersions
Apache Software Foundation · Apache Tomcataffected Apache Tomcat 10 10.0.3 to 10.0.4 ; affected Apache Tomcat 9 9.0.44 ; affected Apache Tomcat 8.5 8.5.64

References

Sources

SourceLicence
CVE List (CVEProject cvelistV5)CVE Program Terms of Use
EPSS (FIRST.org)FIRST — attribution requested
ENISA EUVDENISA — reproduction authorised, source acknowledged
NVD (NIST) via fkie-cad/nvd-json-data-feedsPublic domain — this product uses data from the NVD API but is not endorsed or certified by the NVD