postgresql/doc
Tom Lane 160c025880 libpq: reject extraneous data after SSL or GSS encryption handshake.
libpq collects up to a bufferload of data whenever it reads data from
the socket.  When SSL or GSS encryption is requested during startup,
any additional data received with the server's yes-or-no reply
remained in the buffer, and would be treated as already-decrypted data
once the encryption handshake completed.  Thus, a man-in-the-middle
with the ability to inject data into the TCP connection could stuff
some cleartext data into the start of a supposedly encryption-protected
database session.

This could probably be abused to inject faked responses to the
client's first few queries, although other details of libpq's behavior
make that harder than it sounds.  A different line of attack is to
exfiltrate the client's password, or other sensitive data that might
be sent early in the session.  That has been shown to be possible with
a server vulnerable to CVE-2021-23214.

To fix, throw a protocol-violation error if the internal buffer
is not empty after the encryption handshake.

Our thanks to Jacob Champion for reporting this problem.

Security: CVE-2021-23222
2021-11-08 11:14:56 -05:00
..
src libpq: reject extraneous data after SSL or GSS encryption handshake. 2021-11-08 11:14:56 -05:00
KNOWN_BUGS Remove extra newlines at end and beginning of files, add missing newlines 2010-08-19 05:57:36 +00:00
Makefile Remove maintainer-check target, fold into normal build 2013-10-10 20:11:56 -04:00
MISSING_FEATURES Remove extra newlines at end and beginning of files, add missing newlines 2010-08-19 05:57:36 +00:00
TODO Change documentation references to PG website to use https: not http: 2017-05-20 21:50:47 -04:00