CVE-2026-51300: SQLite Use-After-Free Vulnerability

CVE-2026-51300 Overview

CVE-2026-51300 is a use-after-free vulnerability in the expression parsing and memory management logic of SQLite 3.41. After sqlite3ExprDelete releases an expression object, the program retains the dangling pointer and later accesses member fields of the freed memory. A remote attacker can trigger invalid memory access by submitting crafted SQL queries. Successful exploitation causes application crashes and can leak sensitive memory contents to the attacker. The flaw is classified under CWE-416: Use After Free and affects any application that exposes SQLite query parsing to untrusted input.

Critical Impact
Remote attackers can crash SQLite-backed applications and leak process memory over the network without authentication or user interaction.

Affected Products

SQLite version 3.41
Applications embedding the affected SQLite library
Services exposing SQL query interfaces backed by SQLite 3.41

Discovery Timeline

2026-07-27 - CVE-2026-51300 published to the National Vulnerability Database
2026-07-28 - Last updated in NVD database

Technical Details for CVE-2026-51300

Vulnerability Analysis

The vulnerability resides in SQLite's expression handling path in src/expr.c. During query compilation, sqlite3ExprDelete frees an expression node structure, but the calling code retains a reference to the same pointer. Subsequent parsing operations dereference that stale pointer and read or write fields of an already released heap allocation. Because the freed region can be reused by the allocator for unrelated data, the read returns whatever now occupies that memory. This produces two attacker-useful outcomes: an immediate crash of the SQLite host process and disclosure of adjacent heap contents through error paths or query results. See the SQLite expression source for the affected code region.

Root Cause

The root cause is a lifetime tracking error. sqlite3ExprDelete releases the expression object, yet the parent parser state continues to hold and use the freed pointer instead of clearing it or reallocating. The code path does not enforce a single owner for the expression allocation, which allows a use-after-free to occur when parsing continues past the delete call.

Attack Vector

Exploitation requires only the ability to submit SQL to a vulnerable SQLite 3.41 instance. An attacker crafts a query whose expression structure triggers the delete-and-reuse sequence in the parser. No authentication and no user interaction are required, and the attack traverses the network wherever the SQL interface is reachable. The vulnerability affects confidentiality through memory disclosure and availability through process termination.

No verified public exploit code was available at the time of publication. Refer to the GitHub advisory for CVE-2026-51300 for reproduction details.

Detection Methods for CVE-2026-51300

Indicators of Compromise

Unexpected crashes or segmentation faults in processes linking libsqlite3 version 3.41
SQLite error responses referencing malformed expression trees returned to unauthenticated clients
Anomalous SQL statements with deeply nested or repeatedly redefined expressions from external sources
Core dumps of SQLite host services correlated with inbound network SQL traffic

Detection Strategies

Inventory all software that embeds SQLite and identify instances running the 3.41 release
Enable AddressSanitizer or similar heap validators in non-production builds to surface use-after-free access on sqlite3ExprDelete code paths
Alert on repeated parser errors originating from the same client source address
Correlate application crash telemetry with preceding query payloads to identify probing attempts

Monitoring Recommendations

Forward SQLite host process crash events and application logs to a centralized analytics platform
Monitor egress from database services for unusually sized error responses that may carry leaked memory
Track query rate and error rate spikes on any interface exposing SQL to untrusted clients
Baseline normal SQL statement shapes and alert on outliers containing unusual expression nesting

How to Mitigate CVE-2026-51300

Immediate Actions Required

Identify every deployment using SQLite 3.41 and prioritize systems that accept SQL from untrusted sources
Restrict network exposure of SQLite-backed services to trusted clients only until a fix is applied
Enforce strict SQL input validation and reject queries from unauthenticated network principals
Enable process crash monitoring and automatic restart to limit availability impact

Patch Information

A vendor patch reference was not listed in the NVD entry at the time of publication. Track upstream fixes through the SQLite source repository and upgrade to a release later than 3.41 that clears the dangling pointer after sqlite3ExprDelete. Rebuild and redeploy any application that statically links the affected SQLite version.

Workarounds

Place SQLite behind an application layer that parameterizes queries and blocks direct SQL passthrough from remote clients
Run SQLite host processes with reduced privileges and memory-scrubbing allocators to limit leak value
Deploy web application firewall rules that reject SQL payloads containing pathological expression structures
Isolate SQLite services in dedicated network segments with strict allowlists

bash

# Verify installed SQLite version and locate vulnerable binaries
sqlite3 --version
ldconfig -p | grep libsqlite3
find / -name 'libsqlite3*' -type f 2>/dev/null