CVE-2026-39113 in SQLite
Summary
by MITRE • 08/26/2026
Buffer Overflow vulnerability in SQLite affected version source snapshots/builds containing Fossil check-in 8bdc0d485e3ad0c7a1e818da66f106951d496b05cbe61d12c2c448f2f24b6d5d (Git mirror 169f68ed88b34cb68f720191c64c058f2ccec508, 2026-03-11) and later snapshots/builds allows an attacker to cause a denial of service via the ext/misc/sqlar.c, sqlarUncompressFunc(), sqlar_uncompress(), sqlite3_value_int64(), sqlite3_malloc(int), uncompress() components
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Analysis
by VulDB Data Team • 08/26/2026
The identified vulnerability represents a critical buffer overflow condition within the SQLite database engine, specifically affecting source snapshots and builds that include Fossil check-in 8bdc0d485e3ad0c7a1e818da66f106951d496b05cbe61d12c2c448f2f24b6d and subsequent versions. This flaw is located in the ext/misc/sqlar.c module, which implements support for SQL ARchive files, a feature designed to allow users to store binary data within SQLite databases using standard archive formats like gzip or bzip2. The vulnerability arises during the decompression process when handling potentially malformed or maliciously crafted input archives. Specifically, the issue is triggered through the execution path involving sqlarUncompressFunc, which calls sqlar_uncompress, leading to interactions with sqlite3_value_int64 and sqlite3_malloc before invoking external compression libraries via uncompress functions such as those found in zlib or bzip2.
From a technical perspective, this vulnerability falls under CWE-120, Buffer Copy without Checking Size of Input, which is a subset of the broader category CWE-787 Out-of-bounds Write. The root cause lies in insufficient validation of input data lengths prior to memory allocation and subsequent decompression operations. When an attacker provides a specially crafted SQL ARchive file with manipulated headers or compressed payloads, the application may miscalculate the required buffer size or fail to properly bound-check the destination array during the uncompression process. This allows for writing data beyond the allocated heap boundaries, corrupting adjacent memory structures. The involvement of sqlite3_malloc indicates that the overflow occurs in dynamically allocated memory on the heap, which is particularly dangerous as it can lead to arbitrary code execution if an attacker can control the overwritten content or leverage heap exploitation techniques such as fastbin attacks or use-after-free scenarios following corruption.
The operational impact of this vulnerability is primarily a denial of service against applications relying on SQLite for data storage and retrieval that utilize the SQL ARchive extension. An unauthenticated remote attacker, or one with limited access to execute specific SQL statements involving archive operations, can trigger this buffer overflow by submitting maliciously constructed queries or uploading corrupted archive files through application interfaces that interact with SQLite. The immediate consequence is a crash of the database process due to memory corruption, resulting in service disruption for end-users and potential data loss if transaction logs are compromised during the crash. In more severe scenarios where heap metadata is overwritten effectively, this could escalate into remote code execution, allowing full compromise of the underlying system hosting the SQLite instance. This aligns with ATT&CK technique T1498 Network Denial of Service, as well as potential lateral movement vectors if exploited in a multi-tenant environment or cloud deployment context where database integrity is paramount for application stability and security posture.
Mitigation strategies must focus on immediate patching and defensive coding practices within the affected codebase. Organizations utilizing SQLite versions containing the specified check-in should upgrade to the latest stable release that addresses this specific flaw, ensuring that the sqlar extension has been updated with proper bounds checking before memory allocation and during decompression routines. Developers implementing custom wrappers around SQLite must validate all inputs related to archive formats rigorously, enforcing strict length checks against expected maximums for uncompressed data sizes relative to compressed payloads. Additionally, enabling Address Sanitizer (ASan) or similar runtime error detection tools in development environments can help identify such memory safety issues early in the software lifecycle. For production systems where immediate patching is not feasible, implementing input validation at the application layer to reject suspicious archive structures and restricting access to SQL ARchive functions via least-privilege database user accounts can reduce the attack surface significantly until a permanent fix is deployed.