CVE-2019-16225

Vulnerability

Analysis

CVE-2019-16225 is a vulnerability in py-lmdb version 0.97, a Python binding for the LMDB database [1][4]. The issue lies in the mdb_page_touch function which, for certain values of mp_flags, does not correctly initialize the mc->mc_pg[mc->top] field [1]. This results in an invalid write operation when the library tries to access or modify a page in the memory-mapped database [1].

The attack surface is limited to scenarios where an attacker can supply a malicious data.mdb file [1]. Exploitation requires the victim to open and process this file using a vulnerable version of py-lmdb [1][2]. The exact mp_flags values that trigger this condition are not publicly detailed, but the issue was demonstrated in a proof-of-concept repository [2].

A successful exploit could lead to memory corruption, potentially allowing further exploitation such as arbitrary code execution or denial of service [1][2]. The flaw is classified as a "write to illegal address" [2], indicating that an attacker-controlled write beyond allocated memory boundaries is possible.

Mitigation

Users are advised to upgrade to a patched version of py-lmdb. The project's advisory database indicates that versions after 0.97 have addressed this issue [3]. No official workarounds have been published; the safest mitigation is to avoid opening untrusted data.mdb files with vulnerable software [1].