CVE-2026-6637 PostgreSQL refint allows stack buffer overflow and SQL injection

High 8.8 Published 14 May 2026 Updated 15 May 2026

Unprivileged users can execute arbitrary code via stack overflow or SQL injection in the refint module, requiring specific application configurations.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-6637?

CVE-2026-6637 is a high-severity SQL injection vulnerability in Postgresql Postgresql, published on 14 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

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 if the application declares a user-controlled column as a "refint" cascade primary key and facilitates user-controlled updates to that column. In that case, a SQL injection allows a primary key update value provider to execute arbitrary SQL as the database user performing the primary key update. Versions before PostgreSQL 18.4, 17.10, 16.14, 15.18, and 14.23 are affected.

Weakness: CWE-89, CWE-121

Which versions are affected by CVE-2026-6637?

1 open source package ship an affected version, including postgresql. It affects 1 product.

Package	Affected	Fixed in
`postgresql` Bitnami	All versions	`14.23.0, 15.18.0, 16.14.0, 17.10.0, 18.4.0`

Linux distribution packages (39)

`postgresql` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-contrib` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-contrib-debuginfo` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-debuginfo` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-debugsource` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-docs-debuginfo` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-plperl` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-plperl-debuginfo` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-plpython3` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-plpython3-debuginfo` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-pltcl` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-pltcl-debuginfo` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-private-libs` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-private-libs-debuginfo` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-server` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-server-debuginfo` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-server-devel-debuginfo` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-test-debuginfo` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-upgrade` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-upgrade-debuginfo` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql-upgrade-devel-debuginfo` Red Hat:rhel_e4s:9.2::appstream	All versions	`0:13.23-1.el9_2.3`
`postgresql` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-contrib` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-contrib-debuginfo` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-debuginfo` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-debugsource` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-docs-debuginfo` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-plperl` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-plperl-debuginfo` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-plpython3` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-plpython3-debuginfo` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-pltcl` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-pltcl-debuginfo` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-private-libs` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-private-libs-debuginfo` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-server` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-server-debuginfo` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-server-devel-debuginfo` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`
`postgresql-test-debuginfo` Red Hat:rhel_eus:9.6::appstream	All versions	`0:13.23-1.el9_6.3`

Products include Postgresql Postgresql.

How do I fix CVE-2026-6637?

Upgrade postgresql to a fixed version for your release line: 14.23.0, 15.18.0, 16.14.0 or 17.10.0.

Use parameterised queries everywhere and never build SQL by joining strings. Upgrade affected software first; a web application firewall only buys time. More about SQL injection.

Is CVE-2026-6637 being exploited?

There is no known exploitation of CVE-2026-6637 in the wild and no public exploit code.

All Postgresql Postgresql vulnerabilities

Sources

Also known as ALPINE-CVE-2026-6637, AZL-86837, BELL-CVE-2026-6637, BIT-postgresql-2026-6637, DEBIAN-CVE-2026-6637, ECHO-e69f-5ef2-55d4 and 11 more.