CVE-2026-6637: PostgreSQL 'refint' Module Allows RCE, SQLi
The National Vulnerability Database has detailed CVE-2026-6637, a critical vulnerability in the PostgreSQL ‘refint’ module. This flaw, a stack buffer overflow, enables an unprivileged database user to execute arbitrary code with the privileges of the operating system user running the database. This is a severe privilege escalation vector, allowing a low-privileged user to potentially take full control of the database server.
Beyond the direct RCE, a distinct attack scenario involves applications that declare user-controlled columns as ‘refint’ cascade primary keys and facilitate user-controlled updates to these columns. In such a configuration, a SQL injection vulnerability would allow an attacker to provide a primary key update value, leading to arbitrary SQL execution as the database user performing the update. This broadens the attack surface significantly, impacting applications built on PostgreSQL that handle user input in this specific manner.
Versions of PostgreSQL prior to 18.4, 17.10, 16.14, 15.18, and 14.23 are all affected. The National Vulnerability Database assigns a CVSS score of 8.8 (HIGH), underscoring the urgency for immediate patching. The CWEs associated are CWE-89 (Improper Neutralization of Special Elements used in an SQL Command (‘SQL Injection’)) and CWE-121 (Stack-based Buffer Overflow), highlighting the dual nature of this dangerous vulnerability.
What This Means For You
- If your organization relies on PostgreSQL, this is a critical patch cycle. Immediately identify all PostgreSQL instances running versions older than 18.4, 17.10, 16.14, 15.18, or 14.23. Prioritize patching these systems to mitigate both the remote code execution and potential SQL injection risks. Furthermore, audit your application code for any instances where user-controlled columns are designated as 'refint' cascade primary keys, as these create an additional attack vector.
Related ATT&CK Techniques
🛡️ Detection Rules
3 rules · 6 SIEM formats3 detection rules auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
CVE-2026-6637: PostgreSQL refint Module RCE via Stack Buffer Overflow
title: CVE-2026-6637: PostgreSQL refint Module RCE via Stack Buffer Overflow
id: scw-2026-05-14-ai-1
status: experimental
level: critical
description: |
Detects potential exploitation of CVE-2026-6637 by monitoring the execution of PostgreSQL control utilities (pg_ctl) with arguments that could be indicative of an attacker attempting to leverage the refint module vulnerability for RCE. This rule specifically targets the execution of PostgreSQL binaries in a way that might be abused after a successful stack buffer overflow in the refint module.
author: SCW Feed Engine (AI-generated)
date: 2026-05-14
references:
- https://shimiscyberworld.com/posts/nvd-CVE-2026-6637/
tags:
- attack.execution
- attack.t1059.004
logsource:
category: process_creation
detection:
selection:
Image|startswith:
- 'C:\Program Files\PostgreSQL\'
CommandLine|contains:
- 'pg_ctl start'
- 'pg_ctl restart'
condition: selection
falsepositives:
- Legitimate administrative activity
Source: Shimi's Cyber World · License & reuse
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| CVE-2026-6637 | Buffer Overflow | PostgreSQL module "refint" stack buffer overflow |
| CVE-2026-6637 | RCE | Arbitrary code execution as operating system user running PostgreSQL |
| CVE-2026-6637 | SQLi | SQL injection via user-controlled 'refint' cascade primary key updates |
| CVE-2026-6637 | Affected Version | PostgreSQL versions before 18.4, 17.10, 16.14, 15.18, and 14.23 |
Written by SCW Vulnerability Desk
Source & Attribution
| Source Platform | NVD |
| Channel | National Vulnerability Database |
| Published | May 14, 2026 at 17:16 UTC |
This content was AI-rewritten and enriched by Shimi's Cyber World based on the original source. All intellectual property rights remain with the original author.
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