This USN details multiple PostgreSQL vulnerabilities, including a high-severity flaw (CVE-2026-6473, CVSS 8.8) allowing remote code execution or DoS via large user input, and an SQL injection in pg_createsubscriber (CVE-2026-6476) enabling superuser SQL execution on specific Ubuntu releases. Affected versions are PostgreSQL < 14.23, >=15.0 <15.18, >=16.0 <16.14, >=17.0 <17.10, and >=18.0 <18.4, requiring an upgrade to the corresponding fixed versions (e.g., 14.23, 15.18).
It was discovered that PostgreSQL did not correctly enforce authorization for CREATE TYPE. An attacker could possibly use this issue to execute arbitrary SQL functions. (CVE-2026-6472) It was discovered that PostgreSQL incorrectly handled large user input in multiple server features. An attacker could possibly use this issue to cause PostgreSQL to crash, resulting in a denial of service, or execute arbitrary code. (CVE-2026-6473) It was discovered that PostgreSQL incorrectly handled format strings in the timeofday() function. An attacker could possibly use this issue to obtain sensitive information. (CVE-2026-6474) It was discovered that PostgreSQL incorrectly followed symbolic links in pg_basebackup and pg_rewind. An attacker could possibly use this issue to overwrite local files and execute arbitrary code. (CVE-2026-6475) It was discovered that PostgreSQL had an SQL injection vulnerability in pg_createsubscriber. An attacker could possibly use this issue to execute arbitrary SQL as a superuser. This issue only affected Ubuntu 25.10 and Ubuntu 26.04 LTS. (CVE-2026-6476) It was discovered that PostgreSQL used an unsafe libpq function in large object operations. An attacker could possibly use this issue to overwrite client memory and execute arbitrary code. (CVE-2026-6477) It was discovered that PostgreSQL did not compare MD5-hashed passwords in constant time. An attacker could possibly use this issue to obtain sensitive information. (CVE-2026-6478) It was discovered that PostgreSQL had uncontrolled recursion during SSL and GSS negotiation. An attacker could possibly use this issue to cause a denial of service. (CVE-2026-6479) It was discovered that PostgreSQL incorrectly handled array length mismatches in pg_restore_attribute_stats(). An attacker could possibly use this issue to obtain sensitive information. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-6575) It was discovered that PostgreSQL had a stack buffer overflow in the refint module. An attacker could use this issue to cause PostgreSQL to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2026-6637) It was discovered that PostgreSQL had an SQL injection vulnerability in logical replication REFRESH PUBLICATION. An attacker could possibly use this issue to execute arbitrary SQL. This issue only affected Ubuntu 24.04 LTS, Ubuntu 25.10, and Ubuntu 26.04 LTS. (CVE-2026-6638)