CVE-2026-15742 in PostgreSQL
Summary
by MITRE • 08/13/2026
Integer wraparound in PostgreSQL fuzzystrmatch allows a user to direct writes to a huge range of addresses, executing arbitrary code as the operating system user running the database, via extreme inputs to SQL function levenshtein() or levenshtein_less_equal(). Versions before PostgreSQL 18.5, 17.11, 16.15, 15.19, and 14.24 are affected.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 08/13/2026
This vulnerability represents a critical integer wraparound flaw in PostgreSQL's fuzzystrmatch extension that enables remote code execution through carefully crafted inputs to string similarity functions. The issue manifests in the levenshtein() and levenshtein_less_equal() SQL functions where improper handling of large input values causes integer overflow conditions that can be exploited to manipulate memory addresses. When these functions process extremely long strings, the internal integer calculations wrap around, potentially directing write operations to arbitrary memory locations controlled by the attacker. This vulnerability falls under CWE-191 Integer Underflow/Overflow, specifically representing an integer wraparound scenario where the system fails to properly validate input sizes before performing arithmetic operations. The attack vector is particularly dangerous because it allows privilege escalation from database user level to the operating system user running PostgreSQL, creating a severe security risk for organizations relying on database systems.
The technical exploitation requires understanding how PostgreSQL internally manages memory allocation and string processing within these fuzzy matching functions. When input strings exceed normal processing limits, the integer variables used for indexing and buffer management overflow, causing the system to write data to unexpected memory addresses. This creates opportunities for heap-based buffer overflows or memory corruption that can be leveraged to execute arbitrary code with the privileges of the database service account. The vulnerability affects multiple PostgreSQL versions simultaneously due to shared underlying code paths in the fuzzystrmatch extension, making it a widespread concern across different release branches. Attackers can craft specially formatted SQL queries containing extremely long strings that trigger the integer wraparound condition, potentially leading to complete system compromise.
The operational impact of this vulnerability extends beyond simple privilege escalation as it fundamentally undermines database security boundaries and trust models. Organizations running affected PostgreSQL versions face potential data breaches, unauthorized access to sensitive information, and complete system takeover risks. The vulnerability is particularly concerning in multi-tenant environments or cloud deployments where database users might have limited access but could potentially exploit this flaw to gain elevated privileges across the entire infrastructure. System administrators must consider that even read-only database users with access to these functions could potentially leverage the vulnerability for privilege escalation attacks, making it a significant concern for organizations implementing least privilege security models.
Mitigation strategies should focus on immediate version upgrades to PostgreSQL 18.5, 17.11, 16.15, 15.19, or 14.24, which contain the necessary patches addressing the integer wraparound conditions in the fuzzystrmatch extension. Organizations should also implement input validation measures that limit string lengths accepted by these functions to prevent exploitation attempts. Database administrators should consider disabling the fuzzystrmatch extension entirely if it is not essential for business operations, or restrict access to specific trusted users who require these advanced text matching capabilities. Monitoring systems should be configured to detect unusual patterns of queries involving these functions, as they may indicate attempted exploitation activities. Additionally, implementing network segmentation and privilege separation between database services and application servers can help limit the potential damage from successful exploitation attempts, aligning with ATT&CK technique T1068 for privilege escalation and T1566 for social engineering approaches.