postgres.git / summary / log / commit / refs

commit    fadbe882d16112fd8c5ccf2b73eb9621dbfe130a
Author:   Nathan Bossart <nathan@postgresql.org>
Commit:   Noah Misch <noah@leadboat.com>
Date:     Mon Aug 10 13:38:24 2026 +0000
First released in: 16.15, 17.11, 18.6

    Use value of scram_iterations in mock_scram_secret().
    
    Presently, mock_scram_secret() always uses
    SCRAM_SHA_256_DEFAULT_ITERATIONS, which poses an observable
    response discrepancy hazard when scram_iterations is set to
    something else.  To fix, use the value of the configuration
    parameter instead, and document that unauthenticated users can
    discover the existence of roles with passwords created with
    different iteration counts.
    
    Reported-by: Radim Marek <radim@boringsql.com>
    Author: Nathan Bossart <nathandbossart@gmail.com>
    Reviewed-by: Michael Paquier <michael@paquier.xyz>
    Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
    Reviewed-by: Jacob Champion <champion.p@gmail.com>
    Security: CVE-2026-14672
    Backpatch-through: 16


 doc/src/sgml/config.sgml       | 13 +++++++++++++
 src/backend/libpq/auth-scram.c |  2 +-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3f8cd96d9a1..8a04cdfaaa1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1136,6 +1136,19 @@ include_dir 'conf.d'
         time of encryption. In order to make use of a changed value, a new
         password must be set.
        </para>
+       <note>
+        <para>
+         If a role password was created with a different iteration count than
+         the value of <literal>scram_iterations</literal> specified in the
+         <filename>postgresql.conf</filename> file or on the server command
+         line, an unauthenticated user can discern the existence of the role by
+         observing discrepancies in the server's responses to connection
+         attempts.  If you find this concerning, ensure that all role passwords
+         are created with <literal>scram_iterations</literal> set to the value
+         specified in the <filename>postgresql.conf</filename> file or on the
+         server command line.
+        </para>
+       </note>
       </listitem>
      </varlistentry>
 
diff --git a/src/backend/libpq/auth-scram.c b/src/backend/libpq/auth-scram.c
index 1b9e1cc0cc1..ce9f4ba5eb8 100644
--- a/src/backend/libpq/auth-scram.c
+++ b/src/backend/libpq/auth-scram.c
@@ -722,7 +722,7 @@ mock_scram_secret(const char *username, pg_cryptohash_type *hash_type,
 	encoded_salt[encoded_len] = '\0';
 
 	*salt = encoded_salt;
-	*iterations = SCRAM_SHA_256_DEFAULT_ITERATIONS;
+	*iterations = scram_sha_256_iterations;
 
 	/* StoredKey and ServerKey are not used in a doomed authentication */
 	memset(stored_key, 0, SCRAM_MAX_KEY_LEN);


[parent: 5e5ea74e389b]