Description
In OpenZeppelin <=v4.4.0, initializer functions that are invoked separate from contract creation (the most prominent example being minimal proxies) may be reentered if they make an untrusted non-view external call. Once an initializer has finished running it can never be re-executed. However, an exception put in place to support multiple inheritance made reentrancy possible, breaking the expectation that there is a single execution.
Remediation
References
https://github.com/OpenZeppelin/openzeppelin-contracts/security/advisories/GHSA-9c22-pwxw-p6hx
Related Vulnerabilities
CVE-2020-28448 Vulnerability in npm package multi-ini
CVE-2012-2098 Vulnerability in maven package org.apache.commons:commons-compress
CVE-2019-10746 Vulnerability in maven package org.webjars.npm:mixin-deep
CVE-2019-0221 Vulnerability in maven package org.apache.tomcat:tomcat-catalina
CVE-2017-1000042 Vulnerability in maven package org.webjars.npm:mapbox.js