CVE-2026-6638: SQL injection in PostgreSQL logical replication ALTER SUBSCRIPTION ..

Routine

LOW 3.7UPGRADE

CVE-2026-6638 is a low-severity flaw (CVSS 3.7) affecting postgresql. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 credentials. The attack takes effect at the next REFRESH PUBLICATION. Within major versions 16, 17, and 18, minor versions before PostgreSQL 18.4, 17.10, and 16.14 are affected. Versions before PostgreSQL 16 are unaffected.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	3.7 (Low)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.2% (top 92%)
CISA exploited list	No
Weakness	CWE-89
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: >= 16.0 and < 16.14 · >= 17.0 and < 17.10 · >= 18.0 and < 18.4

Fixed in: 16.14, 17.10, 18.4

Safe to downgrade to: a release before 16.0

1. Check installed version

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

2. UPGRADE to 16.14 (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 16.0 (Debian / Ubuntu)

apt-cache madison postgresql sudo apt install postgresql=<VERSION_BEFORE_16.0> 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_16.0> 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-2026-6638?

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

Is CVE-2026-6638 being exploited?

CVE-2026-6638 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-2026-6638 affect?

CVE-2026-6638 affects postgresql. Severity is low (CVSS 3.7). 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 credentials. The attack takes effect at the next

How urgent is CVE-2026-6638?

Priority 15/100. No elevated risk signals yet.

Software pages

PostgreSQL vulnerabilities

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References

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