CVE-2023-5868: PostgreSQL Information Disclosure Flaw

CVE-2023-5868 Overview

A memory disclosure vulnerability was discovered in PostgreSQL that allows remote authenticated users to access sensitive information by exploiting certain aggregate function calls with 'unknown'-type arguments. When PostgreSQL handles 'unknown'-type values from string literals without proper type designation, it can inadvertently disclose bytes from system memory, potentially revealing confidential information stored in server memory.

This vulnerability exists due to excessive data output in aggregate function calls. An authenticated attacker with the ability to execute SQL queries can craft specific aggregate function invocations that cause the database server to return memory contents beyond the intended data boundaries.

Critical Impact

Authenticated remote users can read portions of PostgreSQL server system memory, potentially exposing sensitive data including credentials, configuration details, or data from other database sessions.

Affected Products

• PostgreSQL (multiple versions up to and including 16.0)
• Red Hat Enterprise Linux 8.x and 9.x
• Red Hat CodeReady Linux Builder EUS (multiple architectures)
• Red Hat Software Collections 1.0

Discovery Timeline

• December 10, 2023 - CVE-2023-5868 published to NVD
• November 4, 2025 - Last updated in NVD database

Technical Details for CVE-2023-5868

Vulnerability Analysis

This memory disclosure vulnerability stems from improper handling of 'unknown'-type arguments within PostgreSQL's aggregate function processing. When aggregate functions receive string literals that lack explicit type designation, the database engine fails to properly bound the memory read operations, resulting in information leakage.

The vulnerability is classified under CWE-686 (Function Call With Incorrect Argument Type), indicating that the root issue involves type handling inconsistencies when processing function arguments. An authenticated user with query execution privileges can leverage this flaw to extract memory contents from the PostgreSQL server process.

The attack requires network access and valid database credentials, but does not require any user interaction or special privileges beyond basic query execution rights. The impact is limited to confidentiality compromise, with no direct effect on data integrity or system availability.

Root Cause

The vulnerability originates from PostgreSQL's type inference system when handling aggregate functions. When a string literal is passed to an aggregate function without explicit type casting, PostgreSQL treats it as an 'unknown' type. The aggregate function processing code fails to properly validate and constrain the memory access when handling these 'unknown'-type values, leading to out-of-bounds memory reads that return unintended data to the query result.

Attack Vector

The attack requires an authenticated connection to a vulnerable PostgreSQL server. An attacker constructs SQL queries that invoke aggregate functions with specially crafted string literal arguments that lack type designation. When the database processes these queries, the improper handling of 'unknown'-type values causes memory beyond the intended boundaries to be included in the query response.

The attacker can potentially retrieve sensitive information residing in server memory, such as data from other sessions, internal configuration values, or fragments of previously processed queries. Multiple queries may be required to extract meaningful data, as the memory disclosure is limited to portions of memory adjacent to the legitimate data being processed.

Detection Methods for CVE-2023-5868

Indicators of Compromise

• Unusual aggregate function queries with untyped string literals in database logs
• Queries attempting multiple variations of aggregate function calls with different string patterns
• Increased query activity from specific user accounts targeting system or sensitive tables
• Abnormal query result sizes that exceed expected data returns

Detection Strategies

• Enable detailed query logging in PostgreSQL (log_statement = 'all') and monitor for suspicious aggregate function usage patterns
• Implement database activity monitoring (DAM) solutions to detect anomalous query patterns
• Review database audit logs for repeated failed or unusual queries from the same user session
• Deploy SentinelOne Singularity to detect and alert on exploitation attempts targeting database servers

Monitoring Recommendations

• Configure PostgreSQL logging to capture all aggregate function calls with enhanced detail
• Set up alerts for query patterns that match known exploitation signatures
• Monitor network traffic to PostgreSQL servers for unusual connection patterns or data exfiltration indicators
• Implement baseline monitoring for normal query behavior to identify statistical anomalies

How to Mitigate CVE-2023-5868

Immediate Actions Required

• Upgrade PostgreSQL to a patched version (16.1, 15.5, 14.10, 13.13, 12.17, or 11.22)
• Review database user privileges and apply least-privilege principles
• Enable comprehensive database query logging for forensic purposes
• Audit recent query logs for potential exploitation attempts

Patch Information

PostgreSQL has released security updates addressing this vulnerability. Patched versions include PostgreSQL 16.1, 15.5, 14.10, 13.13, 12.17, and 11.22. Users should upgrade to these versions or later to remediate the vulnerability.

For Red Hat Enterprise Linux users, multiple security advisories have been published including RHSA-2023:7545, RHSA-2023:7579, and subsequent advisories. Consult the PostgreSQL Security Advisory for complete version-specific guidance.

Workarounds

• Restrict database access to trusted users only until patches can be applied
• Implement network segmentation to limit who can connect to PostgreSQL servers
• Use application-level controls to sanitize and type-cast all SQL query parameters
• Consider temporarily disabling or restricting access to non-essential aggregate functions if operationally feasible

# Verify PostgreSQL version and check if patched
psql --version

# Check installed PostgreSQL package on RHEL/CentOS
rpm -qa | grep postgresql

# Update PostgreSQL on RHEL-based systems
sudo dnf update postgresql*

# Enable detailed query logging for monitoring
# Add to postgresql.conf:
# log_statement = 'all'
# log_min_duration_statement = 0