CVE-2025-31480: PostgreSQL aiven-extras Escalation Flaw

CVE-2025-31480 Overview

CVE-2025-31480 is a privilege escalation vulnerability affecting the aiven-extras PostgreSQL extension. This vulnerability allows attackers to elevate their privileges to superuser within PostgreSQL databases that use the aiven-extras package. The flaw exists because the format function is not schema-prefixed, enabling attackers to exploit untrusted search path issues (CWE-426) to achieve unauthorized privilege escalation.

Critical Impact

Attackers with high privileges can escalate to superuser status within PostgreSQL databases, potentially compromising database integrity, accessing sensitive data across tenants, and executing arbitrary database operations with elevated permissions.

Affected Products

• aiven-extras PostgreSQL extension versions prior to 1.1.16
• PostgreSQL databases utilizing the aiven-extras package
• Aiven managed database services running vulnerable extension versions

Discovery Timeline

• 2025-04-04 - CVE-2025-31480 published to NVD
• 2025-04-07 - Last updated in NVD database

Technical Details for CVE-2025-31480

Vulnerability Analysis

This privilege escalation vulnerability arises from an untrusted search path issue within the aiven-extras PostgreSQL extension. The core problem lies in the use of the format function without proper schema qualification. When PostgreSQL functions are invoked without explicitly specifying their schema, the database engine resolves the function name using the current search_path setting. An attacker who can manipulate the search path can inject a malicious function with the same name in a schema that takes precedence, effectively hijacking the function call.

In the context of aiven-extras, this allows an attacker with existing database privileges to create a trojan format function in a schema positioned earlier in the search path. When legitimate extension code subsequently calls format(), the attacker's malicious version executes instead, running in the security context of the extension—which typically has superuser privileges.

Root Cause

The root cause is classified under CWE-426 (Untrusted Search Path). The aiven-extras extension failed to use schema-qualified function calls (e.g., pg_catalog.format() instead of just format()), leaving it vulnerable to search path manipulation attacks. This oversight allows attackers to shadow built-in PostgreSQL functions with malicious implementations.

Attack Vector

The attack is network-accessible and requires high privileges as a prerequisite. An attacker must have the ability to create functions within a database schema and manipulate the search path. Once positioned, the attacker creates a malicious function matching the unqualified function name used by aiven-extras. When the extension's code executes, the malicious function is invoked with elevated privileges, allowing the attacker to escalate to superuser.

The attack scope is changed (S:C in the CVSS vector), meaning successful exploitation can impact resources beyond the vulnerable component itself—potentially affecting other databases or tenants on the same PostgreSQL instance.

-short_ver = 1.1.15
-last_ver = 1.1.14
+short_ver = 1.1.16
+last_ver = 1.1.15
 long_ver = $(shell git describe --long 2>/dev/null || echo $(short_ver)-0-unknown-g`git describe --always`)
 generated = aiven_extras.control \
 			sql/aiven_extras--$(short_ver).sql \

Source: GitHub Commit Update

Detection Methods for CVE-2025-31480

Indicators of Compromise

• Unexpected user-defined functions named format in non-system schemas
• Modified or suspicious search_path configurations in database sessions
• Unusual privilege escalation events or new superuser accounts appearing in PostgreSQL logs
• Database objects created by users who should not have superuser access

Detection Strategies

• Query pg_proc and pg_namespace to identify any user-created functions shadowing built-in PostgreSQL functions like format
• Monitor PostgreSQL logs for ALTER ROLE or GRANT statements that elevate user privileges unexpectedly
• Implement database activity monitoring to detect search path manipulations
• Review the installed version of aiven-extras using SELECT * FROM pg_available_extensions WHERE name = 'aiven_extras';

Monitoring Recommendations

• Enable detailed PostgreSQL logging with log_statement = 'ddl' to capture function creation and privilege changes
• Configure alerts for any CREATE FUNCTION statements in databases with aiven-extras installed
• Periodically audit database roles and their privilege assignments to detect unauthorized superuser accounts
• Monitor for connections with manipulated search_path session variables

How to Mitigate CVE-2025-31480

Immediate Actions Required

• Upgrade aiven-extras to version 1.1.16 immediately across all affected PostgreSQL instances
• Execute ALTER EXTENSION aiven_extras UPDATE TO '1.1.16' in each database where the extension is installed
• Audit all databases for suspicious user-defined functions that may shadow built-in functions
• Review and restrict privileges for database users to limit who can create functions

Patch Information

Aiven has released version 1.1.16 of the aiven-extras extension to address this vulnerability. The fix ensures that function calls are properly schema-prefixed to prevent search path manipulation attacks. Users should download the update and apply it to all databases using the extension.

For detailed information, refer to the GitHub Security Advisory GHSA-33xh-jqgf-6627 and the security patch commit.

Workarounds

• Restrict function creation privileges using REVOKE CREATE ON SCHEMA public FROM PUBLIC; and similar commands
• Manually audit and remove any suspicious user-defined functions that could shadow PostgreSQL built-ins
• Configure search_path at the database level to prioritize pg_catalog schema
• Limit database access to trusted users until the patch can be applied

# Update aiven-extras extension in each affected database
psql -d your_database -c "ALTER EXTENSION aiven_extras UPDATE TO '1.1.16';"

# Verify the installed version
psql -d your_database -c "SELECT extversion FROM pg_extension WHERE extname = 'aiven_extras';"

# Audit for suspicious format functions outside pg_catalog
psql -d your_database -c "SELECT n.nspname, p.proname FROM pg_proc p JOIN pg_namespace n ON p.pronamespace = n.oid WHERE p.proname = 'format' AND n.nspname != 'pg_catalog';"