Apache Tomcat Concurrent Http11Processor Bug (CVE-2021-43980)
CVE-2021-43980 Published on September 28, 2022
Apache Tomcat: Information disclosure
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 Analysis
CVE-2021-43980 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a small impact on integrity and availability.
Weakness Type
What is a Race Condition Vulnerability?
The program contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently.
CVE-2021-43980 has been classified to as a Race Condition vulnerability or weakness.
Products Associated with CVE-2021-43980
You can be notified by email with stack.watch whenever vulnerabilities like CVE-2021-43980 are published in these products:
Affected Versions
Apache Software Foundation Apache Tomcat:- Version 10.1.0-M1 to 10.1.0-M12 is affected.
- Version 10.0.0-M1 to 10.0.18 is affected.
- Version 9.0.0-M1 to 9.0.60 is affected.
- Version 8.5.0 to 8.5.77 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.