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CVE-2026-14679 is a stack buffer overflow vulnerability discovered in PostgreSQL, one of the world’s most popular open-source relational database management systems. The flaw resides in the argument name matching logic within the PostgreSQL core server, specifically during the processing of functions that utilize OUT parameters. An object creator—a database user with privileges to create or alter functions—can exploit this vulnerability by manipulating the count of OUT parameters in a crafted function call.
The root cause lies in improper bounds checking when the PostgreSQL server matches argument names against internal structures. When a function with an excessive number of OUT parameters is processed, the server writes beyond the allocated stack buffer memory. Notably, the attack is constrained to writing only the byte values `0x0` (NULL) and `0x1` into server memory. While this limitation reduces the immediate potential for arbitrary code execution, it remains a serious concern as it can corrupt adjacent stack variables, leading to unpredictable server behavior, denial of service, or potential privilege escalation.
The vulnerability affects all PostgreSQL versions prior to 18.5, 17.11, 16.15, 15.19, and 14.24. It was patched on August 13, 2026, with the release of these fixed versions. The PostgreSQL project credits Zheng Yu (DepthFirst AI) and ylwangtju for reporting this security issue. The vulnerability carries a CVSS 3.1 base score of 8.2, categorized as HIGH severity. The attack vector is network-based, requires low attack complexity, and no privileges or user interaction, making it remotely exploitable by any authenticated object creator. Given that the vulnerability exists in the core server component, it impacts a wide range of PostgreSQL deployments globally.
DailyCVE Form:
Platform: PostgreSQL
Version: <18.5,<17.11,<16.15,<15.19,<14.24
Vulnerability: Stack Buffer Overflow
Severity: High (8.2 CVSS)
Date: 2026-08-13
Prediction: Already Patched (2026-08-13)
What Undercode Say:
The following commands and code snippets demonstrate how to check your PostgreSQL version and assess exposure to CVE-2026-14679.
Check PostgreSQL Version:
postgres --version or within psql psql -c "SELECT version();"
Check for Vulnerable Versions:
psql -c "SHOW server_version;" | grep -E '^(18.[0-4]|17.[0-9]|16.[0-9]|15.[0-9]|14.[0-9])'
Verify Installed Packages (Debian/Ubuntu):
dpkg -l | grep postgresql | grep -E '18.[0-4]|17.[0-9]|16.[0-9]|15.[0-9]|14.[0-9]'
Verify Installed Packages (RHEL/CentOS):
rpm -qa | grep postgresql | grep -E '18.[0-4]|17.[0-9]|16.[0-9]|15.[0-9]|14.[0-9]'
Simulated Attack Logic (Educational Purpose):
-- The following is a conceptual representation of the attack vector. -- An object creator defines a function with an excessive number of OUT parameters -- to trigger the stack buffer overflow in argument name matching. CREATE OR REPLACE FUNCTION exploit_cve_2026_14679( OUT p1 int, OUT p2 int, OUT p3 int, OUT p4 int, OUT p5 int, OUT p6 int, OUT p7 int, OUT p8 int, OUT p9 int, OUT p10 int, -- [ ... hundreds of additional OUT parameters to overflow the stack ... ] ) AS $$ SELECT 1,2,3,4,5,6,7,8,9,10; $$ LANGUAGE SQL; -- This causes the server to write 0x0 and 0x1 bytes beyond the stack buffer.
Exploit: (Educational Purposes!)
The exploitation process involves the following steps:
- Authentication: The attacker must have valid database credentials with object creation privileges (e.g., `CREATEROLE` or ownership of a schema).
- Crafted Function Definition: The attacker defines a function with a maliciously large number of `OUT` parameters.
- Triggering the Overflow: When the function is parsed and executed, the argument name matching routine copies parameter names into a fixed-size stack buffer without proper bounds checking.
- Memory Corruption: The overflow writes `0x0` and `0x1` bytes into adjacent stack memory, potentially corrupting return addresses, saved frame pointers, or local variables.
- Impact: This corruption can lead to server crashes (denial of service), unexpected query results, or in more sophisticated scenarios, arbitrary code execution if critical control data is overwritten.
Conceptual Proof-of-Concept (Educational):
-- Attempt to create a function with an extreme number of OUT parameters. -- (This is a simplified illustration; actual exploitation requires precise -- parameter count to exceed the stack buffer limit.) DO $$ DECLARE sql TEXT := 'CREATE OR REPLACE FUNCTION exploit() RETURNS RECORD AS $$ SELECT '; i INT; BEGIN FOR i IN 1..10000 LOOP sql := sql || 'NULL, '; END LOOP; sql := sql || 'NULL; $$ LANGUAGE SQL;'; EXECUTE sql; END $$;
Protection:
To protect against CVE-2026-14679, the following measures are recommended:
1. Upgrade Immediately: Apply the official patch by upgrading to PostgreSQL version 18.5, 17.11, 16.15, 15.19, 14.24, or any later release.
2. Verify Upgrade: After upgrading, confirm the new version is running:
psql -c "SELECT version();"
3. Restrict Object Creation Privileges: As a temporary workaround, limit the ability to create or alter functions to only trusted database users. Revoke unnecessary `CREATEROLE` and schema write permissions.
REVOKE CREATE ON SCHEMA public FROM PUBLIC;
4. Monitor Database Logs: Watch for unusual function creation patterns or server crashes that may indicate attempted exploitation.
5. Apply Vendor Security Updates: Follow your operating system or distribution’s package manager to apply the latest PostgreSQL security updates.
Debian/Ubuntu sudo apt-get update && sudo apt-get upgrade postgresql RHEL/CentOS sudo yum update postgresql
Impact:
- Confidentiality: None, as per CVSS vector.
- Integrity: Low impact, as the attack can only write `0x0` and `0x1` bytes, limiting data corruption capabilities.
- Availability: High impact, as stack corruption can lead to server crashes and denial of service.
- Scope: Unchanged, meaning the vulnerability does not affect resources beyond the vulnerable component.
- Exploitability: Remote, with low attack complexity and no required privileges, making it a significant risk for exposed database instances.
- Affected Deployments: All PostgreSQL instances running versions prior to the fixed releases are vulnerable, including cloud, on-premise, and containerized environments.
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Sources:
Reported By: nvd.nist.gov
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