CVE-2026-18024 in PostgreSQL
Summary
by MITRE • 08/13/2026
Buffer over-read in PostgreSQL ascii() SQL function allows a user to disclose up to 3 bytes after the end of a specific allocation, via a crafted text value. This is the same class of defect that CVE-2026-2006 fixed, though this instance has less impact. Versions before PostgreSQL 18.5, 17.11, 16.15, 15.19, and 14.24 are affected.
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Analysis
by VulDB Data Team • 08/13/2026
This vulnerability represents a classic buffer over-read condition within PostgreSQL's ascii() SQL function implementation, where an attacker can manipulate input data to cause the system to read memory locations beyond the allocated buffer boundaries. The flaw occurs when processing crafted text values through the ascii() function, which is designed to return the ASCII value of a character but instead triggers unintended memory access patterns that can expose up to three bytes of adjacent memory contents. This type of vulnerability falls under the CWE-125 weakness category, specifically addressing out-of-bounds read conditions that can lead to information disclosure. The vulnerability affects multiple PostgreSQL versions including 14 through 18, with specific patch releases noted for each major version line, indicating this is a well-documented class of memory safety issue that has been previously addressed in CVE-2026-2006.
The operational impact of this vulnerability stems from its ability to provide attackers with potential access to sensitive information stored in adjacent memory locations, which could include database connection details, user credentials, or other confidential data structures. While the disclosed information is limited to only three bytes, the cumulative effect of multiple such operations could potentially allow an attacker to reconstruct larger pieces of sensitive data through repeated exploitation attempts. The vulnerability operates at the application level within the SQL function processing layer, making it accessible through standard database query execution paths and potentially exploitable by users with basic database access privileges. This aligns with ATT&CK technique T1566.001 for initial access through valid accounts and T1005 for data from local system.
Security mitigations for this vulnerability primarily involve applying the vendor-provided patches to affected PostgreSQL versions, which typically include memory bounds checking and proper input validation within the ascii() function implementation. Organizations should prioritize patching all affected systems in their environment, particularly those handling sensitive data or operating in regulated compliance domains where information disclosure could have significant consequences. Additional defensive measures include implementing strict database access controls to limit who can execute potentially malicious SQL functions, monitoring for unusual query patterns that might indicate exploitation attempts, and conducting regular security assessments of database configurations. The vulnerability's relatively limited impact compared to CVE-2026-2006 suggests it may not require immediate emergency patching, but organizations should still treat it as a medium-severity risk requiring prompt remediation within their standard update cycles.