PostgreSQL 18.3 → 18.4

Vulnerabilities fixed by this upgrade

• 8.8 CVE-2026-6475 Symlink following in PostgreSQL pg_basebackup plain format and in pg_rewind allows an origin superuser to overwrite local files, e.g. /var/lib/postgres/.bashrc, that hijack the operating system acc…
• 7.2 CVE-2026-6476 SQL injection in PostgreSQL pg_createsubscriber allows an attacker with pg_create_subscription rights to execute arbitrary SQL as a superuser. The attack takes effect when pg_createsubscriber next…
• 8.8 CVE-2026-6477 Use of inherently dangerous function PQfn(..., result_is_int=0, ...) in PostgreSQL libpq lo_export(), lo_read(), lo_lseek64(), and lo_tell64() functions allows the server superuser to overwrite a c…
• 6.5 CVE-2026-6478 Covert timing channel in comparison of MD5-hashed password in PostgreSQL authentication allows an attacker to recover user credentials sufficient to authenticate. This does not affect scram-sha-25…
• 7.5 CVE-2026-6479 Uncontrolled recursion in PostgreSQL SSL and GSS negotiation allows an attacker able to connect to a PostgreSQL AF_UNIX socket to achieve sustained denial of service. If SSL and GSS are both disab…
• 4.3 CVE-2026-6575 Buffer over-read in PostgreSQL function pg_restore_attribute_stats() accepts array values of unmatched length, which causes query planning to read past end of one array. This allows a table mainta…
• 8.8 CVE-2026-6637 Stack buffer overflow in PostgreSQL module "refint" allows an unprivileged database user to execute arbitrary code as the operating system user running the database. A distinct attack is possible…
• 3.7 CVE-2026-6638 SQL injection in PostgreSQL logical replication ALTER SUBSCRIPTION ... REFRESH PUBLICATION allows a subscriber table creator to execute arbitrary SQL with the subscription's publication-side creden…
• 5.4 CVE-2026-6472 Missing authorization in PostgreSQL CREATE TYPE allows an object creator to hijack other queries that use search_path to find user-defined types, including extension-defined types. That is to say,…
• 8.8 CVE-2026-6473 Integer wraparound in multiple PostgreSQL server features allows an unprivileged database user to cause the server to undersize an allocation and write out-of-bounds. This may execute arbitrary co…
• 4.3 CVE-2026-6474 Externally-controlled format string in PostgreSQL timeofday() function allows an attacker to retrieve portions of server memory, via crafted timezone zones. Versions before PostgreSQL 18.4, 17.10,…

Breaking changes

• breaking Fix incomplete removal of relation references in RestrictInfo structs during join removal (Tom Lane) This oversight has been shown to result in planner failures such as unexpected “FULL JOIN is only supported with merge-joinable or hash-joinable join conditions” errors. It may also have caused… in 18.4

Security changes

• security Prevent unbounded recursion while processing startup packets (Michael Paquier) A malicious client could crash the connected backend by alternating rejected SSL and GSS encryption requests indefinitely. The PostgreSQL Project thanks Calif.io (in collaboration with Claude and Anthropic Research) for… in 18.4
• security Fix assorted integer overflows in memory-allocation calculations (Tom Lane, Nathan Bossart, Heikki Linnakangas) Various places were incautious about the possibility of integer overflow in calculations of how much memory to allocate. Overflow would lead to allocating a too-small buffer which the… in 18.4
• security Properly quote subscription names in pg_createsubscriber (Nathan Bossart) The given subscription name was inserted into SQL commands without quoting, so that SQL injection could be achieved in the (perhaps unlikely) case that the subscription name comes from an untrusted source. The PostgreSQL… in 18.4
• security Properly quote object names in logical replication origin checks (Pavel Kohout) ALTER SUBSCRIPTION ... REFRESH PUBLICATION interpolated schema and relation names into SQL commands without quoting them, allowing execution of arbitrary SQL on the publisher. The PostgreSQL Project thanks Pavel Kohout… in 18.4
• security Reject over-length options in ts_headline() (Michael Paquier) The StartSel, StopSel and FragmentDelimiter strings must not exceed 32Kb in length, but this was not checked for. An over-length value would typically crash the server. The PostgreSQL Project thanks Xint Code for reporting this problem.… in 18.4
• security Detect faulty input when restoring attribute MCV statistics (Michael Paquier) The statistics restore functions were insufficiently careful about validating most-common-value statistics, and would accept values that could crash the planner later on. The PostgreSQL Project thanks Jeroen Gui for… in 18.4
• security Guard against malicious time zone names in timeofday() and pg_strftime() (Tom Lane) A crafted time zone setting could pass % sequences to snprintf(), potentially causing crashes or disclosure of server memory. Another path to similar results was to overflow the limited-size output buffer used by… in 18.4
• security When creating a multirange type, ensure the user has CREATE privilege on the schema specified for the multirange type (Jelte Fennema-Nio) The multirange type can be put into a different schema than its parent range type, but we neglected to apply the required privilege check when doing so. The… in 18.4
• security Use timing-safe string comparisons in authentication code (Michael Paquier) Use timingsafe_bcmp() instead of memcmp() or strcmp() when checking passwords, hashes, etc. It is not known whether the data dependency of those functions is usefully exploitable in any of these places, but in the… in 18.4
• security Mark PQfn() as unsafe, and avoid using it within libpq (Nathan Bossart) For a non-integral result type, PQfn() is not passed the size of the output buffer, so it cannot check that the data returned by the server will fit. A malicious server could therefore overwrite client memory. This is… in 18.4
• security Prevent path traversal in pg_basebackup and pg_rewind (Michael Paquier) These applications failed to validate output file paths read from their input, so that a malicious source could overwrite any file writable by these applications. Constrain where data can be written by rejecting paths that are… in 18.4
• security Guard against field overflow within contrib/intarray's query_int type and contrib/ltree's ltxtquery type (Tom Lane) Parsing of these query structures did not check for overflow of 16-bit fields, so that construction of an invalid query tree was possible. This can crash the server when executing… in 18.4
• security Guard against overly long values of contrib/ltree's lquery type (Michael Paquier) Values with more than 64K items caused internal overflows, potentially resulting in stack smashes or wrong answers. The PostgreSQL Project thanks Vergissmeinnicht, A1ex, and Jihe Wang for reporting this problem.… in 18.4
• security Prevent SQL injection and buffer overruns in contrib/spi (Nathan Bossart) check_foreign_key() was insufficiently careful about quoting key values, and also used fixed-length buffers for constructing queries. While this module is only meant as example code, it still shouldn't contain such dangerous… in 18.4
• security Prevent buffer overruns when parsing an affix file for an Ispell dictionary (Tom Lane) A corrupt or malicious affix file could crash the server. This is not considered a security issue because text search configuration files are presumed trustworthy, but it still seems worth fixing. in 18.4
• security Ensure that tuplestore data structures are internally consistent even after an error (Tom Lane) The code was previously careless about this, which is fine most of the time but is problematic for the tuplestore backing a WITH HOLD cursor. In v15 and before this leads to easily-reproducible crashes;… in 18.4

Every release in between