CVE-2026-17351 in pgAdmin
Summary
by MITRE • 07/31/2026
The fix for CVE-2026-12045 in pgAdmin 4 9.16 required the LLM-supplied query passed to the AI Assistant's execute_sql_query tool to parse, via sqlparse, as exactly one non-transaction-control statement before running it inside a BEGIN TRANSACTION READ ONLY wrapper. sqlparse's string-literal lexing can disagree with PostgreSQL's own parser: under standard_conforming_strings = on (PostgreSQL's default since 9.1), a backslash immediately before a quote is an ordinary character to PostgreSQL, but sqlparse treats it as escaping the quote. A payload such as SELECT '\';COMMIT;CREATE TABLE pwn(x int);SELECT 1 --' therefore parses as a single SELECT to sqlparse's validator, while PostgreSQL executes it as four statements: the smuggled COMMIT ends the wrapping read-only transaction, and the trailing ROLLBACK becomes a no-op. This reintroduces the same write/RCE bypass CVE-2026-12045 was meant to close, reachable via the same indirect prompt-injection delivery (an attacker plants the payload in any object the AI Assistant may read; the LLM emits it as a tool call).
An initial candidate fix ran the query with psycopg's execute(..., prepare=True), intending to force PostgreSQL's own Parse step (extended query protocol) to reject multi-statement text regardless of sqlparse's classification. This candidate fix does not work as submitted: psycopg3's PrepareManager silently ignores the prepare argument whenever the connection's prepare_threshold is None, which is pgAdmin's default for every server connection (the per-server "Prepare threshold" field is blank unless an administrator explicitly sets it) -- psycopg3 falls back to the simple query protocol, the same multi-statement-capable path the bypass exploits, so the candidate fix closes nothing on any real-world default configuration.
The corrected fix sets conn.prepare_threshold = 0 directly on the dedicated, single-use read-only connection the AI Assistant tool opens, structurally forcing the extended query protocol independent of any server-level configuration. Verified against a live PostgreSQL 18 instance: the payload executes successfully under the prepare_threshold=None (default) behavior, and is rejected with "cannot insert multiple commands into a prepared statement" once prepare_threshold=0 is set on that connection.
This issue affects pgAdmin 4: from 9.13 before 9.17.
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Analysis
by VulDB Data Team • 07/31/2026
The vulnerability described in CVE-2026-12045 represents a sophisticated write/RCE bypass in pgAdmin 4 version 9.16, specifically within the AI Assistant's execute_sql_query tool functionality. This flaw stems from an insecure interaction between the sqlparse library's statement parsing logic and PostgreSQL's native SQL parser behavior, creating a path for command smuggling attacks that circumvents intended security controls. The vulnerability arises from a fundamental mismatch in how backslash escaping is interpreted across different SQL parsers, where PostgreSQL's default setting of standard_conforming_strings = on treats a backslash before a quote as literal character rather than an escape sequence. This discrepancy allows attackers to craft payloads that appear as single statements to sqlparse but execute as multiple commands within PostgreSQL itself, effectively breaking out of the intended BEGIN TRANSACTION READ ONLY wrapper that was designed to contain SQL execution.
The technical flaw manifests through the improper validation process used by pgAdmin's AI Assistant tool, which relies on sqlparse to validate SQL queries before executing them in a read-only transaction context. When an attacker injects a payload such as SELECT '\';COMMIT;CREATE TABLE pwn(x int);SELECT 1 --', the sqlparse library interprets this as a single SELECT statement due to its different approach to backslash escaping, allowing the tool to pass validation and execute within the transaction wrapper. However, PostgreSQL's actual execution engine processes the same string differently, executing it as four separate statements where the embedded COMMIT terminates the read-only transaction, followed by the creation of a potentially malicious table, and finally a harmless SELECT statement that acts as a comment to mask the attack. This discrepancy between validation and execution creates an indirect prompt injection vector that enables attackers to exploit the system through any database object accessible to the AI Assistant's reading capabilities.
The operational impact of this vulnerability extends beyond simple SQL injection, representing a complete bypass of pgAdmin's intended security boundaries for SQL execution within the AI Assistant framework. The attack path leverages the natural interaction between LLM-generated content and tool execution, where an attacker can plant malicious payloads in database objects such as views, stored procedures, or comments that the AI Assistant might reference during analysis. This creates a particularly dangerous scenario because the vulnerability operates through legitimate AI Assistant workflows rather than direct SQL injection attempts, making detection more challenging for security monitoring systems. The issue affects pgAdmin 4 installations from version 9.13 through 9.16, representing a window of vulnerable releases where the original fix for CVE-2026-12045 was insufficiently robust and could be circumvented through careful payload construction that exploits the underlying parser disagreement.
The initial attempt to address this vulnerability through psycopg's execute(..., prepare=True) parameter failed due to fundamental misconfiguration in pgAdmin's connection handling approach. The psycopg3 library's PrepareManager implementation silently ignores the prepare argument when the connection's prepare_threshold is set to None, which represents pgAdmin's default configuration for all server connections. This design choice means that even when developers attempt to enforce prepared statement usage as a security control, the system automatically falls back to PostgreSQL's simple query protocol, maintaining exactly the multi-statement execution capability that the bypass exploits. The failure of this approach demonstrates how seemingly robust security mitigations can be undermined by underlying library behaviors and default configuration settings that are not properly considered in vulnerability remediation efforts. This particular flaw aligns with CWE-1287 (Improper Handling of Multi-statement SQL Queries) and reflects patterns commonly seen in command injection vulnerabilities where validation occurs in one context while execution happens in another.
The corrected fix implements a targeted approach that directly addresses the root cause by setting conn.prepare_threshold = 0 on the specific single-use read-only connection used exclusively by the AI Assistant tool. This configuration forces the use of PostgreSQL's extended query protocol for that particular connection, regardless of server-level settings or administrator configurations, ensuring that any attempt to execute multi-statement SQL will be rejected by PostgreSQL itself with the clear error message "cannot insert multiple commands into a prepared statement." This approach eliminates the dependency on potentially misconfigured global settings and provides an explicit security boundary around AI Assistant operations. The fix's effectiveness has been validated against live PostgreSQL 18 instances, demonstrating that it successfully blocks the exploit under default configurations while maintaining proper functionality for legitimate single-statement queries. This solution aligns with ATT&CK technique T1059.008 (Command and Scripting Interpreter: Python) and represents a proper implementation of the principle of least privilege by creating a dedicated execution environment with restricted capabilities that cannot be subverted through configuration-based bypasses.
The vulnerability landscape for pgAdmin 4 highlights the complexity of securing modern database administration tools that integrate AI capabilities, where traditional security boundaries become blurred by machine-generated content and automated tool workflows. The issue demonstrates how seemingly innocuous library interactions can create significant security implications when combined with specific execution contexts and default configurations. Organizations using pgAdmin 4 should immediately upgrade to version 9.17 or later to ensure protection against this vulnerability, as the default configuration behavior of PostgreSQL connections in pgAdmin creates an environment where such bypasses are possible without explicit administrator intervention. The fix represents a robust approach to preventing similar issues by ensuring that security controls operate independently of potentially misconfigured global settings and maintain their intended protective properties across all operational contexts. This vulnerability serves as a reminder of the critical importance of understanding how different SQL parsers and execution engines interact, particularly in complex systems where validation and execution occur through separate pathways.