CVE-2026-6471 in PostgreSQL
Summary
by MITRE • 08/13/2026
Missing authorization in PostgreSQL logical decoding allows a non-superuser holding REPLICATION privilege to dlopen any file visible to the operating system account running the server, via the choice of logical decoding plugin. This in turn runs arbitrary code as that account. Versions before PostgreSQL 18.6, 17.11, 16.15, 15.19, and 14.24 are affected.
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Analysis
by VulDB Data Team • 08/31/2026
This vulnerability represents a critical authorization bypass flaw in PostgreSQL logical decoding functionality that fundamentally undermines the database's security model. The issue stems from insufficient access controls within the logical decoding plugin system, where non-superuser accounts possessing only the REPLICATION privilege can exploit this weakness to load arbitrary shared libraries through the dlopen() system call. This architectural oversight creates a path for privilege escalation and code execution directly on the database server operating system level.
The technical exploitation occurs when a malicious user leverages their REPLICATION privilege to specify a logical decoding plugin that utilizes dlopen() to load arbitrary shared libraries from the filesystem. Since the logical decoding process runs under the privileges of the PostgreSQL server account, this creates an arbitrary code execution vector where the attacker's malicious library can execute with the same elevated permissions as the database service. The vulnerability specifically affects PostgreSQL versions prior to 18.5, 17.11, 16.15, 15.19, and 14.24, indicating this was a persistent flaw across multiple major releases.
The operational impact of this vulnerability is severe as it allows attackers to bypass traditional database security boundaries and potentially gain complete control over the underlying operating system where PostgreSQL is hosted. An attacker could use this privilege escalation to access sensitive data, modify database contents, install backdoors, or escalate privileges further within the network infrastructure. This vulnerability particularly affects environments where PostgreSQL is configured with REPLICATION privileges for legitimate administrative purposes but where those users should not have unrestricted file system access.
This weakness aligns with CWE-863 (Incorrect Authorization) and represents a clear violation of the principle of least privilege in database security architecture. The ATT&CK framework categorizes this as privilege escalation through exploitation of software vulnerabilities, specifically targeting the execution of malicious code with elevated privileges. Organizations should immediately implement mitigations including upgrading to patched PostgreSQL versions, restricting REPLICATION privileges to only trusted superuser accounts, and monitoring for unusual logical decoding plugin usage patterns. Additionally, implementing proper file system access controls and regular security audits can help detect and prevent exploitation attempts of this class of vulnerability.
The vulnerability demonstrates the critical importance of comprehensive authorization checking in database systems where multiple privilege levels exist. The flaw essentially allows any user with REPLICATION rights to escalate their privileges beyond what was intended by the database administrator, creating a potential pathway for complete system compromise. Regular patch management becomes essential as this vulnerability could be exploited by attackers who gain access to accounts with REPLICATION privileges through other means, such as compromised credentials or misconfigured permissions. The fix implemented in newer PostgreSQL versions addresses the core authorization issue by ensuring that only superuser accounts can load arbitrary plugins through the logical decoding system.