CVE-2026-3172

A flaw was found in pgvector. A buffer overflow vulnerability in the parallel Hierarchical Navigable Small World (HNSW) index build process allows a database user to exploit this flaw. This can lead to the disclosure of sensitive data from other database relations or cause the database server to crash, resulting in a denial of service.

A buffer overflow during parallel HNSW index builds can be exploited by a database user, potentially leading to information disclosure from other database relations or a denial of service by crashing the database server, although the high impact on availability and confidentiality Red Hat Product Security team has rated this as having a moderate severity. This happens because, besides the low privileges required, to successfully exploit this flaw the attack needs to win a race condition among several worker threads which may be a task considered of a high complexity.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, restrict the use of parallel index builds in PostgreSQL. This can be achieved by setting the max_parallel_workers_per_gather parameter to 0 in the postgresql.conf file. This configuration change may impact the performance of other parallel operations within PostgreSQL. A restart of the PostgreSQL service is required for the changes to take effect.