Vulnerability in Apache Tomcat
CVE-2021-43980
The simplified implementation of blocking reads and writes introduced in Tomcat 10 and back-ported to Tomcat 9.0.47 onwards exposed a long standing (but extremely hard to trigger) concurrency bug in Apache Tomcat 10.1.0 to 10.1.0-M12, 10.0.0-M1 to 10.0.18, 9.0.0-M1 to 9.0.60 and 8.5.0 to 8.5.77 that could cause client connections to share an Http11Processor instance resulting in responses, or part responses, to be received by the wrong client.
Vulnerability class: Race Condition
EPSS: 0.019 (77.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 3.7 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N.
Affected products
- Apache Tomcat — versions 10.1.0
- Apache Software Foundation Tomcat — versions 10.1.0-M1 to 10.1.0-M12, 10.0.0-M1 to 10.0.18, 9.0.0-M1 to 9.0.60
- Debian Debian_linux — versions 10.0, 11.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security@apache.org (Mailing List, Vendor Advisory)
- security@apache.org (mailing-list, Mailing List, Third Party Advisory)
- security@apache.org (mailing-list, Mailing List, Third Party Advisory)
- security@apache.org (vendor-advisory, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-43980?
- CVE-2021-43980 is a low-severity vulnerability in Apache Tomcat, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 3.7/10. Published 2022-09-28.
- How severe is CVE-2021-43980?
- Low severity. CVSS v3 base score is 3.7 out of 10.
- Is CVE-2021-43980 known to be exploited?
- 4 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.