Authentication Bypass by Primary Weakness

Summary

libcurl would reuse a previously created connection even when some mTLS config related option had been changed that should have prohibited reuse.Affected versions are curl 7.7 through 8.20.0. libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, some TLS settings related to client certificates were left out from the configuration match checks, making them match too easily. In particular options related to the private key.