Security Issues
---------------
Two security holes have been closed by this release:
CVE-2016-5423: certain nested CASE expressions can cause the server to crash.
CVE-2016-5424: database and role names with embedded special characters can allow code injection during administrative operations like pg_dumpall.
The fix for the second issue also adds an option, -reuse-previous, to psql's \connect command. pg_dumpall will also refuse to handle database and role names containing line breaks after the update. For more information on these issues and how they affect backwards-compatibility, see the Release Notes.
Bug Fixes and Improvements
--------------------------
This update also fixes a number of bugs reported in the last few months. Some of these issues affect only version 9.5, but many affect all supported versions:
Fix misbehaviors of IS NULL/IS NOT NULL with composite values
Fix three areas where INSERT ... ON CONFLICT failed to work properly with other SQL features.
Make INET and CIDR data types properly reject bad IPv6 values
Prevent crash in "point ## lseg" operator for NaN input
Avoid possible crash in pg_get_expr()
Fix several one-byte buffer over-reads in to_number()
Don't needlessly plan query if WITH NO DATA is specified
Avoid crash-unsafe state in expensive heap_update() paths
Fix hint bit update during WAL replay of row locking operations
Avoid unnecessary "could not serialize access" with FOR KEY SHARE
Avoid crash in postgres -C when the specified variable is a null string
Fix two issues with logical decoding and subtransactions
Ensure that backends see up-to-date statistics for shared catalogs
Prevent possible failure when vacuuming multixact IDs in an upgraded database
When a manual ANALYZE specifies columns, don't reset changes_since_analyze
Fix ANALYZE's overestimation of n_distinct for columns with nulls
Fix bug in b-tree mark/restore processing
Fix building of large (bigger than shared_buffers) hash indexes
Prevent infinite loop in GiST index build with NaN values
Fix possible crash during a nearest-neighbor indexscan
Fix "PANIC: failed to add BRIN tuple" error
Prevent possible crash during background worker shutdown
Many fixes for issues in parallel pg_dump and pg_restore
Make pg_basebackup accept -Z 0 as no compression
Make regression tests safe for Danish and Welsh locales
This release closes security hole CVE-2016-2193, where a query plan might get reused for more than one ROLE in the same session. This could cause the wrong set of Row Level Security (RLS) policies to be used for the query.
The update also fixes CVE-2016-3065, a server crash bug triggered by using pageinspect with BRIN index pages. Since an attacker might be able to expose a few bytes of server memory, this crash is being treated as a security issue.
packages. postgresql95-upgrade is gone, the pg_upgrade tool is shipped
with postgresql95-client now.
Major enhancements in PostgreSQL 9.5 include:
Allow INSERTs that would generate constraint conflicts to be turned into
UPDATEs or ignored
Add GROUP BY analysis features GROUPING SETS, CUBE and ROLLUP
Add row-level security control
Create mechanisms for tracking the progress of replication, including
methods for identifying the origin of individual changes during logical
replication
Add Block Range Indexes (BRIN)
Substantial performance improvements for sorting
Substantial performance improvements for multi-CPU machines
