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Import CVE-2025-4207, CVE-2025-8713, CVE-2026-6475, CVE-2026-6477 and CVE-2026-6637 fixes from upstream (45fe7e0, 44ba3f5, 415badc, 0c83fe8, e3a1f83, 8053235, 77b2d18) - #25

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This PR cherry-picks 7 upstream commits for five security fixes.

All seven applied cleanly: no manual conflict resolution was required.

nmisch and others added 7 commits August 21, 2026 14:47
Start the file with static functions not specific to pe_test_vectors
tests.  This way, new tests can use them without disrupting the file's
layout.  Change report_result() PQExpBuffer arguments to plain strings.
Back-patch to v13 (all supported versions), for the next commit.

Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Backpatch-through: 13
Security: CVE-2025-4207
(cherry picked from commit 45fe7e0)
With GB18030 as source encoding, applications could crash the server via
SQL functions convert() or convert_from().  Applications themselves
could crash after passing unterminated GB18030 input to libpq functions
PQescapeLiteral(), PQescapeIdentifier(), PQescapeStringConn(), or
PQescapeString().  Extension code could crash by passing unterminated
GB18030 input to jsonapi.h functions.  All those functions have been
intended to handle untrusted, unterminated input safely.

A crash required allocating the input such that the last byte of the
allocation was the last byte of a virtual memory page.  Some malloc()
implementations take measures against that, making the SIGSEGV hard to
reach.  Back-patch to v13 (all supported versions).

Author: Noah Misch <noah@leadboat.com>
Author: Andres Freund <andres@anarazel.de>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Backpatch-through: 13
Security: CVE-2025-4207
(cherry picked from commit 44ba3f5)
Commit e2d4ef8 (the fix for CVE-2017-7484) added security checks
to the selectivity estimation functions to prevent them from running
user-supplied operators on data obtained from pg_statistic if the user
lacks privileges to select from the underlying table. In cases
involving inheritance/partitioning, those checks were originally
performed against the child RTE (which for plain inheritance might
actually refer to the parent table). Commit 553d2ec then extended
that to also check the parent RTE, allowing access if the user had
permissions on either the parent or the child. It turns out, however,
that doing any checks using the child RTE is incorrect, since
securityQuals is set to NULL when creating an RTE for an inheritance
child (whether it refers to the parent table or the child table), and
therefore such checks do not correctly account for any RLS policies or
security barrier views. Therefore, do the security checks using only
the parent RTE. This is consistent with how RLS policies are applied,
and the executor's ACL checks, both of which use only the parent
table's permissions/policies. Similar checks are performed in the
extended stats code, so update that in the same way, centralizing all
the checks in a new function.

In addition, note that these checks by themselves are insufficient to
ensure that the user has access to the table's data because, in a
query that goes via a view, they only check that the view owner has
permissions on the underlying table, not that the current user has
permissions on the view itself. In the selectivity estimation
functions, there is no easy way to navigate from underlying tables to
views, so add permissions checks for all views mentioned in the query
to the planner startup code. If the user lacks permissions on a view,
a permissions error will now be reported at planner-startup, and the
selectivity estimation functions will not be run.

Checking view permissions at planner-startup in this way is a little
ugly, since the same checks will be repeated at executor-startup.
Longer-term, it might be better to move all the permissions checks
from the executor to the planner so that permissions errors can be
reported sooner, instead of creating a plan that won't ever be run.
However, such a change seems too far-reaching to be back-patched.

Back-patch to all supported versions. In v13, there is the added
complication that UPDATEs and DELETEs on inherited target tables are
planned using inheritance_planner(), which plans each inheritance
child table separately, so that the selectivity estimation functions
do not know that they are dealing with a child table accessed via its
parent. Handle that by checking access permissions on the top parent
table at planner-startup, in the same way as we do for views. Any
securityQuals on the top parent table are moved down to the child
tables by inheritance_planner(), so they continue to be checked by the
selectivity estimation functions.

Author: Dean Rasheed <dean.a.rasheed@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Noah Misch <noah@leadboat.com>
Backpatch-through: 13
Security: CVE-2025-8713
(cherry picked from commit 415badc)
pg_rewind and pg_basebackup could be fed paths from rogue endpoints that
could overwrite the contents of the client when received, achieving path
traversal.

There were two areas in the tree that were sensitive to this problem:
- pg_basebackup, through the astreamer code, where no validation was
performed before building an output path when streaming tar data.  This
is an issue in v15 and newer versions.
- pg_rewind file operations for paths received through libpq, for all
the stable branches supported.

In order to address this problem, this commit adds a helper function in
path.c, that reuses path_is_relative_and_below_cwd() after applying
canonicalize_path().  This can be used to validate the paths received
from a connection point.  A path is considered invalid if any of the two
following conditions is satisfied:
- The path is absolute.
- The path includes a direct parent-directory reference.

Reported-by: XlabAI Team of Tencent Xuanwu Lab
Reported-by: Valery Gubanov <valerygubanov95@gmail.com>
Author: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Backpatch-through: 14
Security: CVE-2026-6475
(cherry picked from commit 0c83fe8)
When result_is_int is set to 0, PQfn() cannot validate that the
result fits in result_buf, so it will write data beyond the end of
the buffer when the server returns more data than requested.  Since
this function is insecurable and obsolete, add a warning to the top
of the pertinent documentation advising against its use.

The only in-tree caller of PQfn() is the frontend large object
interface.  To fix that, add a buf_size parameter to
pqFunctionCall3() that is used to protect against overruns, and use
it in a private version of PQfn() that also accepts a buf_size
parameter.

Reported-by: Yu Kunpeng <yu443940816@live.com>
Reported-by: Martin Heistermann <martin.heistermann@unibe.ch>
Author: Nathan Bossart <nathandbossart@gmail.com>
Reviewed-by: Noah Misch <noah@leadboat.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Etsuro Fujita <etsuro.fujita@gmail.com>
Security: CVE-2026-6477
Backpatch-through: 14
(cherry picked from commit e3a1f83)
Maliciously crafted key value updates could achieve SQL injection
within check_foreign_key().  To fix, ensure new key values are
properly quoted and escaped in the internally generated SQL
statements.  While at it, avoid potential buffer overruns by
replacing the stack buffers for internally generated SQL statements
with StringInfo.

Reported-by: Nikolay Samokhvalov <nik@postgres.ai>
Author: Nathan Bossart <nathandbossart@gmail.com>
Reviewed-by: Noah Misch <noah@leadboat.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Fujii Masao <masao.fujii@gmail.com>
Security: CVE-2026-6637
Backpatch-through: 14
(cherry picked from commit 8053235)
When an UPDATE statement triggers check_foreign_key() with the
action set to "cascade", it generates more UPDATE statements to
modify the key values in referencing relations.  If a new key value
is NULL, SPI_getvalue() returns a NULL pointer, which is
subsequently passed to quote_literal_cstr(), causing a segfault.
To fix, skip quoting when a new key value is NULL and insert an
unquoted NULL keyword instead.

Oversight in commit 260e977.  While the refint documentation
recommends marking primary key columns NOT NULL, the aforementioned
scenario accidentally worked on platforms where snprintf()
substitutes "(null)" for NULL pointers.  Note that for
character-type columns, the old code quoted "(null)" as a string
literal, so this didn't always produce correct results.  But it
still seems better to fix this than to reject cases that previously
worked.

Reported-by: Nikita Kalinin <n.kalinin@postgrespro.ru>
Author: Ayush Tiwari <ayushtiwari.slg01@gmail.com>
Reviewed-by: Pierre Forstmann <pierre.forstmann@gmail.com>
Discussion: https://postgr.es/m/19476-bd04ea6241345303%40postgresql.org
Backpatch-through: 14
(cherry picked from commit 77b2d18)
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5 participants