pgjdbc, the PostgreSQL JDBC Driver, versions 42.7.4 through 42.7.13 pads a value that is shorter than its declared length with bytes left in its send buffer instead of zeros, and the server stores those bytes as part of the value. The bytes are messages the driver sent earlier on the same connection: SQL text and parameter values of recent statements, which on a pooled connection can come from other requests. Each padded value can carry up to 8192 bytes of this traffic, or 16320 bytes on a connection with GSS encryption. The padding happens when an application declares a length larger than the data it supplies, through PreparedStatement.setObject with a ByteStreamWriter, CopyIn.writeToCopy, PGCopyOutputStream.write, LargeObject.write, or Blob.setBytes. The driver accepts these calls without an error. An attacker who can make the application store such a value and read it back can collect earlier traffic. Applications whose declared lengths always match their data are not affected. Versions 42.7.3 and earlier pad with zeros.

pgjdbc is an open source postgresql JDBC Driver. From 42.7.4 and until 42.7.7, when the PostgreSQL JDBC driver is configured with channel binding set to required (default value is prefer), the driver would incorrectly allow connections to proceed with authentication methods that do not support channel binding (such as password, MD5, GSS, or SSPI authentication). This could allow a man-in-the-middle attacker to intercept connections that users believed were protected by channel binding requirements. This vulnerability is fixed in 42.7.7.

A weakness was found in postgresql-jdbc before version 42.2.5. It was possible to provide an SSL Factory and not check the host name if a host name verifier was not provided to the driver. This could lead to a condition where a man-in-the-middle attacker could masquerade as a trusted server by providing a certificate for the wrong host, as long as it was signed by a trusted CA.