In security-restricted operations, block enqueue of at-commit user code.
Specifically, this blocks DECLARE ... WITH HOLD and firing of deferred
triggers within index expressions and materialized view queries. An
attacker having permission to create non-temp objects in at least one
schema could execute arbitrary SQL functions under the identity of the
bootstrap superuser. One can work around the vulnerability by disabling
autovacuum and not manually running ANALYZE, CLUSTER, REINDEX, CREATE
INDEX, VACUUM FULL, or REFRESH MATERIALIZED VIEW. (Don't restore from
pg_dump, since it runs some of those commands.) Plain VACUUM (without
FULL) is safe, and all commands are fine when a trusted user owns the
target object. Performance may degrade quickly under this workaround,
however. Back-patch to 9.5 (all supported versions).
Reviewed by Robert Haas. Reported by Etienne Stalmans.
Security: CVE-2020-25695
Branch
------
REL9_6_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/ff3de4c21a462f2da773848c53faedac88d6e54d
Modified Files
--------------
contrib/postgres_fdw/connection.c | 4 +++
src/backend/access/transam/xact.c | 13 +++++-----
src/backend/commands/portalcmds.c | 5 ++++
src/backend/commands/trigger.c | 12 +++++++++
src/test/regress/expected/privileges.out | 42 ++++++++++++++++++++++++++++++++
src/test/regress/sql/privileges.sql | 34 ++++++++++++++++++++++++++
6 files changed, 104 insertions(+), 6 deletions(-)