CVE-2018-25304 in Free Download Manager
Summary
by MITRE • 04/29/2026
Free Download Manager 2.0 Build 417 contains a local buffer overflow vulnerability in the URL import functionality that allows attackers to trigger a structured exception handler (SEH) chain exploitation. Attackers can craft a malicious URL file that, when imported through the File > Import > Import lists of downloads menu, causes a buffer overflow in the Location header response that overwrites the SEH chain and executes arbitrary code.
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Analysis
by VulDB Data Team • 06/26/2026
The vulnerability in Free Download Manager version 2.0 Build 417 represents a critical local buffer overflow flaw within the URL import functionality that presents significant security risks to affected systems. This issue stems from inadequate input validation and memory management within the application's handling of URL lists, specifically when processing the Location header response during import operations. The vulnerability manifests when users attempt to import maliciously crafted URL files through the File > Import > Import lists of downloads menu interface, creating a dangerous attack vector that can be exploited by adversaries with minimal privileges.
The technical implementation of this vulnerability follows a classic buffer overflow pattern where insufficient bounds checking allows attackers to overwrite memory structures within the application's execution context. When processing the Location header response from maliciously crafted URLs, the software fails to properly validate the length of input data before copying it into fixed-size buffers. This flaw directly enables structured exception handler chain exploitation as described in the vulnerability description, allowing attackers to manipulate the SEH chain and redirect program execution flow. The buffer overflow occurs at a specific memory location where the SEH frame pointer is stored, providing attackers with precise control over the execution environment.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with potential persistence mechanisms within the target system. Successful exploitation can result in arbitrary code execution with the privileges of the affected user account, potentially leading to complete system compromise if the application runs with elevated permissions. This vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and demonstrates how improper input validation can create opportunities for privilege escalation attacks. The attack surface is particularly concerning given that the vulnerability requires only user interaction through legitimate import functionality, making it difficult to detect and prevent without proper security controls.
Mitigation strategies should focus on immediate application updates from the vendor to address the identified buffer overflow conditions in the URL import handling code. System administrators should implement network-based restrictions preventing access to potentially malicious download sources and consider deploying application whitelisting solutions to limit execution of unauthorized software versions. The vulnerability's characteristics align with ATT&CK technique T1059.007 for command and scripting interpreter usage, as successful exploitation would likely involve executing malicious payloads through the compromised application interface. Additionally, organizations should conduct thorough security assessments of all download management applications in use, particularly those handling external URL data, to identify similar buffer overflow vulnerabilities that could be exploited in similar attack scenarios.
The exploitability of this vulnerability is enhanced by the fact that it requires no elevated privileges for initial access and leverages legitimate application functionality to deliver malicious payloads. This makes it particularly dangerous in enterprise environments where users may import download lists from untrusted sources or where social engineering attacks target employees to import compromised URL files. The SEH chain manipulation technique employed in this exploit is a well-documented method for bypassing modern security protections, including stack canaries and DEP mechanisms, making the vulnerability particularly resilient against standard mitigation approaches. Security monitoring should specifically track import operations from suspicious sources and implement behavioral analysis to detect anomalous usage patterns that might indicate exploitation attempts.