CVE-2025-29087: SQLite Buffer Overflow Vulnerability

CVE-2025-29087 Overview

CVE-2025-29087 is an integer overflow vulnerability in SQLite affecting versions 3.44.0 through 3.49.0. The flaw resides in the concat_ws() SQL function, which improperly calculates the size of its result buffer when handling large separator arguments. An attacker who can control the separator string (for example, supplying 2MB or more of data) triggers an integer overflow during size calculation. The undersized malloc allocation results in memory being written beyond the end of the heap-allocated buffer. SQLite released version 3.49.1 to address the issue.

Critical Impact

Attacker-controlled input to concat_ws() causes heap memory corruption, leading to denial of service and potential exploitation depending on the SQLite-embedded application.

Affected Products

• SQLite 3.44.0 through 3.49.0
• Applications embedding vulnerable SQLite versions
• SQLite builds prior to 3.49.1

Discovery Timeline

• 2025-04-07 - CVE-2025-29087 published to NVD
• 2025-04-30 - Last updated in NVD database

Technical Details for CVE-2025-29087

Vulnerability Analysis

The vulnerability is classified as an integer overflow [CWE-190] in SQLite's concat_ws() SQL function. This function concatenates string arguments with a caller-supplied separator. SQLite calculates the total output buffer size by multiplying the separator length by the number of intervening positions and adding the argument lengths.

When the separator length exceeds approximately 2MB, the size computation overflows a 32-bit integer. The result is a smaller-than-required value passed to malloc(). SQLite then writes the full concatenated output into the undersized buffer, corrupting adjacent heap memory.

The attack vector is network-reachable for any application that exposes SQL execution to remote input. The primary observed impact is availability loss through process crashes, though heap corruption can extend to integrity violations depending on allocator state.

Root Cause

The root cause is an unchecked arithmetic operation in the buffer-size calculation inside the concat_ws() implementation. SQLite does not validate whether the cumulative size of the separator multiplied across all join positions exceeds the integer range used for the allocation request. The truncated value bypasses the allocator's ability to reserve adequate space.

Attack Vector

An attacker submits a SQL query that invokes concat_ws() with a large attacker-controlled separator argument. Any interface that forwards user input into SQL statements — web applications, sync services, or embedded query engines — can act as the delivery channel. The malformed query triggers the overflow during query execution, corrupting the heap and typically crashing the SQLite process.

The vulnerability mechanism is documented in the SQLite Release Log 3.49.1 and the SQLite CVE Documentation. A proof-of-concept demonstrating the overflow trigger is available in the GitHub Gist PoC.

Detection Methods for CVE-2025-29087

Indicators of Compromise

• Unexpected SQLite process crashes or segmentation faults during query execution
• SQL queries containing concat_ws() calls with separator arguments exceeding 2MB
• Application logs reporting malloc failures or heap corruption errors tied to SQLite
• Abnormally large request bodies submitted to endpoints that interact with SQLite

Detection Strategies

• Inventory all applications, libraries, and appliances bundling SQLite and identify versions in the 3.44.0 through 3.49.0 range
• Inspect query logs for invocations of concat_ws() with oversized string parameters
• Deploy runtime memory-safety instrumentation (AddressSanitizer, Valgrind) in pre-production builds to flag heap overflows
• Correlate web application firewall logs with downstream SQLite errors to identify probing attempts

Monitoring Recommendations

• Alert on repeated SQLite crash signals across application fleets
• Monitor SQL query length and parameter size distributions for outliers
• Track patch status of embedded SQLite builds in third-party software via SBOM tooling

How to Mitigate CVE-2025-29087

Immediate Actions Required

• Upgrade SQLite to version 3.49.1 or later across all systems and embedded products
• Audit application dependencies and container images for vulnerable SQLite versions
• Restrict untrusted user input from reaching concat_ws() until the patched library is deployed
• Engage vendors of third-party software bundling SQLite to confirm patched release availability

Patch Information

The SQLite project fixed the integer overflow in version 3.49.1. Details are published in the SQLite Release Log 3.49.1. The fix corrects the buffer-size calculation in concat_ws() to prevent integer truncation when the separator is large. All downstream products embedding SQLite should rebuild and redistribute with the patched library.

Workarounds

• Filter or reject SQL inputs that pass separator arguments larger than a safe threshold to concat_ws()
• Disable or restrict access to interfaces that permit arbitrary SQL execution from untrusted users
• Enforce length limits on input fields that feed concatenation functions in SQL statements

# Verify installed SQLite version
sqlite3 --version

# Example input-size guardrail in application code (pseudocode)
if (length(user_separator) > 1048576) {
    reject_request("separator too large");
}