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From: Noah Misch <noah@leadboat.com>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Fix out-of-bound reads with ascii() for invalid multibyte charac
Date: Mon, 10 Aug 2026 13:41:28 +0000
Message-ID: <E1wtQFs-00000000yF7-2M3u@gemulon.postgresql.org> (raw)

Fix out-of-bound reads with ascii() for invalid multibyte characters

This commit addresses two defects in this SQL function, the code
assuming that:
- The user-supplied string was long enough to contain a character of the
length implied by the first byte.  It is possible to provide in input
data that was able to disclose a few bytes of server memory, allowing
out-of-bound reads.
- Specific bytes had values within the expected range, using a set of
assertions to validate them.  The assertions could be triggered on
invalid input.  These are replaced by tests and error reports.

Reported-by: Hcamael <baiyjrh@gmail.com>
Author: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Backpatch-through: 14
Security: CVE-2026-18024

Branch
------
REL_17_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/849da82105395fa4d06f877db8edc62158167941
Author: Michael Paquier <michael@paquier.xyz>

Modified Files
--------------
src/backend/utils/adt/oracle_compat.c  | 25 ++++++++++++++++++++-----
src/test/regress/expected/encoding.out | 19 +++++++++++++++++++
src/test/regress/sql/encoding.sql      | 12 ++++++++++++
3 files changed, 51 insertions(+), 5 deletions(-)



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