CVE-2026-6638

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Last Modified: UTC

Moderate Moderate severity What does this mean?
3.7 CVSS v3 Score Breakdown

Description

A flaw was found in PostgreSQL. This SQL injection vulnerability exists within the logical replication feature, specifically when using the ALTER SUBSCRIPTION ... REFRESH PUBLICATION command. A malicious subscriber table creator can exploit this flaw to execute arbitrary SQL commands with the elevated privileges of the subscription's publication-side credentials. The attack is triggered when the REFRESH PUBLICATION command is next executed.

Statement

SQL injection in PostgreSQL logical replication allows a subscriber-side table creator to execute arbitrary SQL on the publisher using the subscription's publication-side credentials. ALTER SUBSCRIPTION ... REFRESH PUBLICATION interpolates subscriber-side schema and relation names into SQL sent to the publisher without properly quoting them; a crafted relation name can therefore inject arbitrary SQL that runs with the privileges of the subscription's publication-side role the next time REFRESH PUBLICATION is executed. Exploitation requires the attacker to already hold table-creation privileges on the subscriber database, for logical replication to be configured with an untrusted subscriber-side user, and for a privileged user to subsequently run REFRESH PUBLICATION, which limits the practical attack surface for most default deployments. Only PostgreSQL major versions 16, 17, and 18 are affected; versions prior to 16 do not include the vulnerable code path (introduced by commit 875693019053b8897ec3983e292acbb439b088c3).

Mitigation

Upgrade to PostgreSQL 18.4, 17.10, or 16.14 (matching your major version) or later, which corrects the identifier quoting used when the subscriber's apply worker sends the REFRESH PUBLICATION SQL to the publisher. Versions prior to PostgreSQL 16 are not affected. As a temporary mitigation, restrict CREATE TABLE / table-ownership privileges on subscriber databases to trusted roles only, avoid configuring logical replication subscriptions for untrusted subscriber-side users, and scope the subscription's publication-side credentials to the minimum privileges necessary.

Additional information

External References

Affected Packages and Issued Red Hat Security Errata

Unless explicitly stated as not affected, all previous versions of packages in any minor update stream of a product listed here should be assumed vulnerable, although may not have been subject to full analysis.

Products / Services Components State Errata
Red Hat Enterprise Linux 10 postgresql18 Fixed RHSA-2026:27742
Red Hat Enterprise Linux 10 postgresql16 Fixed RHSA-2026:27743
Red Hat Enterprise Linux 10.0 Extended Update Support postgresql16 Fixed RHSA-2026:27718
Red Hat Enterprise Linux 8 postgresql:16 Fixed RHSA-2026:28143
Red Hat Enterprise Linux 9 postgresql:16 Fixed RHSA-2026:26203
Red Hat Enterprise Linux 9 postgresql:18 Fixed RHSA-2026:26204
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions postgresql:16 Fixed RHSA-2026:26524
Red Hat Enterprise Linux 9.6 Extended Update Support postgresql:16 Fixed RHSA-2026:26525
Red Hat Hardened Images postgresql17-main Fixed RHSA-2026:21182
Red Hat Hardened Images postgresql18-main Fixed RHSA-2026:22878

Common Vulnerability Scoring System (CVSS) Score Details

Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authorities (CNA) source for its products and services (see Red Hat classifications ).

CVSS v3 Score Breakdown

Red Hat NVD cve.org
CVSS v3 Base Score 3.7 8.8 3.7
Attack Vector Network Network Network
Attack Complexity High Low High
Privileges Required Low Low Low
User Interaction Required None Required
Scope Unchanged Unchanged Unchanged
Confidentiality Impact Low High Low
Integrity Impact Low High Low
Availability Impact None High None

CVSS v3 Vector

Red Hat CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N

NVD CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

cve.org CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

 For open source software shipped by multiple vendors, the CVSS base scores may vary for each vendor's version depending on the version they ship, how they ship it, the platform, and even how the software is compiled. This makes scoring of vulnerabilities difficult for third-party vulnerability databases such as NVD that only provide a single CVSS base score for each vulnerability. Red Hat scores reflect how a vulnerability affects our products specifically.

For more information, see https://access.redhat.com/solutions/762393.

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?
  • "Under investigation" doesn't necessarily mean that the product is affected by this vulnerability. It only means that our Analysis Team is still working on determining whether the product is affected and how it is affected.
  • "Affected" means that our Analysis Team has determined that this product is affected by this vulnerability and might release a fix to address this in the near future.

What can I do if my product is listed as "Will not fix"?

 A "will not fix" status means that a fix for an affected product version is not planned or not possible due to complexity, which may create additional risk.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Upgrade to a supported product version that includes a fix for this vulnerability (recommended).
  • Apply a mitigation (if one exists).
  • Open a This content is not included.support case to request a prioritization of releasing a fix for this vulnerability.

What can I do if my product is listed as "Fix deferred"?

 A deferred status means that a fix for an affected product version is not guaranteed due to higher-priority development work.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Apply a mitigation (if one exists).
  • Open a This content is not included.support case to request a prioritization of releasing a fix for this vulnerability.
  • Red Hat Engineering focuses on addressing high-priority issues based on their complexity or limited lifecycle support. Therefore, lower-priority issues will not receive immediate fixes.

What is a mitigation?

 A mitigation is an action that can be taken to reduce the impact of a security vulnerability, without deploying any fixes.

I have a Red Hat product but it is not in the above list, is it affected?

 The listed products were found to include one or more of the components that this vulnerability affects. These products underwent a thorough evaluation to determine their affectedness by this vulnerability. Note that layered products (such as container-based offerings) that consume affected components from any of the products listed in this table may be affected and are not represented.

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

 In order to maintain code stability and compatibility, Red Hat usually does not rebase packages to entirely new versions. Instead, we backport fixes and new features to an older version of the package we distribute. This can result in some security scanners that only consider the package version to report the package as vulnerable. To avoid this, we suggest that you use an approved vulnerability scanner from our This content is not included.Red Hat Vulnerability Scanner Certification program.

My product is listed as "Out of Support Scope". What does this mean?

 When a product is listed as "Out of Support Scope", it means a vulnerability with the impact level assigned to this CVE is no longer covered by its current support lifecycle phase. The product has been identified to contain the impacted component, but analysis to determine whether it is affected or not by this vulnerability was not performed. The product should be assumed to be affected. Customers are advised to apply any mitigation options documented on this page, consider removing or disabling the impacted component, or upgrade to a supported version of the product that has an update available.