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Vulnerability record · CVE-2021-41079 · published 16 September 2021

CVE-2021-41079: Apache tomcat improper input validation vulnerability

Apache · Tomcat

Apache Tomcat 8.5.0 to 8.5.63, 9.0.0-M1 to 9.0.43 and 10.0.0-M1 to 10.0.2 did not properly validate incoming TLS packets. When Tomcat was configured to use NIO+OpenSSL or NIO2+OpenSSL for TLS, a specially crafted packet could be used to trigger an infinite loop resulting in a denial of service.

7.5 CVSS 3.1 High EPSS 7.2% · top 5.9% CWE-20 · Improper input validationCWE-835 · CWE-835
7.5CVSS 3.1 base score, v2 4.3
7.2%EPSS exploitation probability, 30 days
NoNot in CISA KEV
3Affected product versions listed by NVD
12References
17 Jun 2026Last modified by NVD

Description

Apache Tomcat 8.5.0 to 8.5.63, 9.0.0-M1 to 9.0.43 and 10.0.0-M1 to 10.0.2 did not properly validate incoming TLS packets. When Tomcat was configured to use NIO+OpenSSL or NIO2+OpenSSL for TLS, a specially crafted packet could be used to trigger an infinite loop resulting in a denial of service.

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

Affected products

3 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://lists.apache.org/thread.html/r6b6b674e3f168dd010e67dbe6848b866e2acf26371452fdae313b98a%40%3Cusers.tomcat.apache.
https://lists.apache.org/thread.html/rb4de81ac647043541a32881099aa6eb5a23f1b7fd116f713f8ab9dbe%40%3Cdev.tomcat.apache.or
https://lists.apache.org/thread.html/rccdef0349fdf4fb73a4e4403095446d7fe6264e0a58e2df5c6799434%40%3Cannounce.tomcat.apac Mailing ListVendor Advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00012.html Mailing ListThird Party Advisory
https://security.netapp.com/advisory/ntap-20211008-0005/ Third Party Advisory
https://www.debian.org/security/2021/dsa-4986 Third Party Advisory
https://lists.apache.org/thread.html/r6b6b674e3f168dd010e67dbe6848b866e2acf26371452fdae313b98a%40%3Cusers.tomcat.apache.
https://lists.apache.org/thread.html/rb4de81ac647043541a32881099aa6eb5a23f1b7fd116f713f8ab9dbe%40%3Cdev.tomcat.apache.or
https://lists.apache.org/thread.html/rccdef0349fdf4fb73a4e4403095446d7fe6264e0a58e2df5c6799434%40%3Cannounce.tomcat.apac Mailing ListVendor Advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00012.html Mailing ListThird Party Advisory
https://security.netapp.com/advisory/ntap-20211008-0005/ Third Party Advisory
https://www.debian.org/security/2021/dsa-4986 Third Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2021-41079), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.