Description

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.

Mitigation

We recommend upgrading to a version of this component that is not vulnerable to this specific issue.

Note: If this component is included as a bundled/transitive dependency of another component, there may not be an upgrade path. In this instance, we recommend contacting the maintainers who included the vulnerable package. Alternatively, we recommend investigating alternative components or a potential mitigating control.

Related links:

• http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-43980

• https://lists.apache.org/thread/3jjqbsp6j88b198x5rmg99b1qr8ht3g3

• https://tomcat.apache.org/security-10.html

• https://tomcat.apache.org/security-8.html

• https://tomcat.apache.org/security-9.html

• https://access.redhat.com/security/cve/cve-2021-43980