CVE-2026-6637: Stack buffer overflow in PostgreSQL module "refint" allows an unprivileged database user to execute arbitrary

Routine

HIGH 8.8UPGRADE

CVE-2026-6637 is a high-severity flaw (CVSS 8.8) affecting postgresql. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 data

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.4% (top 69%)
CISA exploited list	No
Weakness	CWE-89, CWE-121
Published	2026-05-14
Last modified	2026-06-17

Publisher (CNA): PostgreSQL · Vendor: postgresql

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-14 14:16 UTCPublished CVE record published
2026-06-17 11:01 UTCUpdated Record last modified

postgresql postgresql UPGRADE

Affected: < 14.23 · >= 15.0 and < 15.18 · >= 16.0 and < 16.14 · >= 17.0 and < 17.10 · >= 18.0 and < 18.4

Fixed in: 14.23, 15.18, 16.14, 17.10, 18.4

Safe to downgrade to: a release before 15.0

1. Check installed version

apt-cache policy postgresql || rpm -q postgresql || postgresql --version

2. UPGRADE to 14.23 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade postgresql

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade postgresql

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 15.0 (Debian / Ubuntu)

apt-cache madison postgresql sudo apt install postgresql=<VERSION_BEFORE_15.0> sudo apt-mark hold postgresql

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list postgresql sudo dnf downgrade postgresql-<VERSION_BEFORE_15.0> sudo dnf versionlock add postgresql

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-6637?

postgresql: upgrade to 14.23, 15.18, 16.14, 17.10, 18.4. Exact commands for each OS are on this page.

Is CVE-2026-6637 being exploited?

CVE-2026-6637 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-6637 affect?

CVE-2026-6637 affects postgresql. Severity is high (CVSS 8.8). 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-controll

How urgent is CVE-2026-6637?

Priority 38/100. High severity

Software pages

PostgreSQL vulnerabilities

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References

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