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CVE-2021-30639

29
FAUCET Score

CVE-2021-30639 is a Denial of Service (DoS) vulnerability in Apache Tomcat versions 10.0.3-10.0.4, 9.0.44, and 8.5.64, stemming from an error in non-blocking I/O error handling that prevents subsequent requests from being processed. This vulnerability has a CVSS score of 7.5 (HIGH), indicating it can be exploited remotely with low attack complexity and no user interaction, leading to a complete loss of availability. While the vulnerability affects several Apache and McAfee products, there is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
8.5.64CPE matchmatch criteria
cpe:2.3:a:apache:tomcat:8.5.64:*:*:*:*:*:*:*
9.0.44CPE matchmatch criteria
cpe:2.3:a:apache:tomcat:9.0.44:*:*:*:*:*:*:*
10.0.3CPE matchmatch criteria
cpe:2.3:a:apache:tomcat:10.0.3:*:*:*:*:*:*:*
10.0.4CPE matchmatch criteria
cpe:2.3:a:apache:tomcat:10.0.4:*:*:*:*:*:*:*
< 5.10.0CPE matchmatch criteria
cpe:2.3:a:mcafee:epolicy_orchestrator:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
6.89%
Probability of exploitation in next 30 days
EPSS Percentile
93.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0689 is in the 89th percentile among its peer group of 51,506 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

mavenpatch availablevia ghsa
Product: org.apache.tomcat:tomcatFixed in: 10.0.5
mavenpatch availablevia ghsa
Product: org.apache.tomcat:tomcatFixed in: 9.0.45
mavenpatch availablevia ghsa
Product: org.apache.tomcat:tomcatFixed in: 8.5.65
oraclepatch availablevia nvd_reference
View patch

Vendor Advisories (2)

mavenGHSA-44qp-qhfv-c7f6high

Improper Handling of Exceptional Conditions in Apache Tomcat

Aug 13, 2021
redhatCVE-2021-30639Important

tomcat: non-blocking I/O error flag is not reset between requests

Jul 12, 2021

References

kc.mcafee.com / corporate/index
Third Party Advisory
lists.apache.org / thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf%40%3Cdev.tomcat.apache.org%3E
lists.apache.org / thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf%40%3Cusers.tomcat.apache.org%3E
lists.apache.org / thread.html/rd84fae1f474597bdf358f5bdc0a5c453c507bd527b83e8be6b5ea3f4%40%3Cannounce.tomcat.apache.org%3E
Mailing ListVendor Advisory
security.gentoo.org / glsa/202208-34
Third Party Advisory
security.netapp.com / advisory/ntap-20210827-0007
Third Party Advisory
oracle.com / security-alerts/cpujan2022.html
PatchThird Party Advisory