CVE-2016-0773 in PostgreSQL
Summary
by MITRE
PostgreSQL before 9.1.20, 9.2.x before 9.2.15, 9.3.x before 9.3.11, 9.4.x before 9.4.6, and 9.5.x before 9.5.1 allows remote attackers to cause a denial of service (infinite loop or buffer overflow and crash) via a large Unicode character range in a regular expression.
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Analysis
by VulDB Data Team • 07/08/2022
The vulnerability identified as CVE-2016-0773 represents a critical security flaw in PostgreSQL database systems affecting multiple version branches including 9.1.20, 9.2.15, 9.3.11, 9.4.6, and 9.5.1. This issue resides in the regular expression processing functionality of the database engine and constitutes a denial of service vulnerability that can be exploited remotely by attackers. The flaw specifically manifests when the system processes regular expressions containing large Unicode character ranges, creating conditions that lead to either infinite loops or buffer overflow scenarios that ultimately result in system crashes.
The technical implementation of this vulnerability stems from insufficient input validation within PostgreSQL's regular expression engine. When a malicious user submits a regular expression containing an excessive Unicode character range, the system's pattern matching algorithm becomes vulnerable to computational exhaustion. This occurs because the regular expression engine fails to properly handle boundary conditions for Unicode character sets, particularly when dealing with ranges that exceed normal operational parameters. The flaw operates at the level of the regular expression processing module, which is responsible for interpreting and executing pattern matching operations against database content. This vulnerability directly maps to CWE-129, which describes improper validation of length or count values, and CWE-131, which covers incorrect calculation of buffer or data sizes. The attack vector is classified as network-based remote exploitation, requiring no authentication to execute successfully.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire database systems and the applications dependent upon them. When exploited, the vulnerability can cause database servers to enter infinite loop states or experience buffer overflows that result in immediate crashes, leading to complete service unavailability. This denial of service condition affects database availability and can be particularly devastating in production environments where database uptime is critical for business operations. The vulnerability affects all versions of PostgreSQL prior to the specified patch releases, making it a widespread concern for organizations running older database versions. The impact is amplified by the fact that regular expressions are commonly used in database queries, making this vulnerability particularly dangerous as it can be triggered through normal database operations.
Mitigation strategies for CVE-2016-0773 primarily involve immediate patching of affected PostgreSQL installations to the latest available versions. Organizations should prioritize upgrading their database systems to versions 9.1.20, 9.2.15, 9.3.11, 9.4.6, or 9.5.1 respectively, depending on their current version. Additionally, implementing network-level controls such as firewalls and access control lists can help limit exposure by restricting access to database services from untrusted networks. Database administrators should also consider implementing input validation measures that sanitize regular expression inputs before processing, particularly for user-supplied data. The vulnerability demonstrates the importance of regular security updates and patch management programs, as it represents a classic example of how seemingly minor input validation flaws can result in significant system compromise. Organizations should also implement monitoring solutions that can detect abnormal database behavior patterns that might indicate exploitation attempts, aligning with ATT&CK technique T1499.004 for network disruption and service denial. Security teams should conduct thorough vulnerability assessments to identify all PostgreSQL installations within their environment and ensure comprehensive coverage of the patching process.