CVE-2020-37234: 
Tonec Internet Download Manager vulnerability analysis and mitigation

CVE-2020-37234 is a classic buffer overflow vulnerability in the Scheduler component of Internet Download Manager (IDM) version 6.38.12, developed by Tonec Inc. The flaw allows local attackers to crash the application by pasting oversized input (exceeding 5,000 bytes) into the 'Open the following file when done' field, triggering a denial of service condition. It carries a CVSS v3.1 base score of 6.2 (Medium) and a CVSS v4.0 base score of 6.9 (Medium) (GitHub Advisory). The CVE was published to the NVD and GitHub Advisory Database on May 16, 2026, and was assigned GHSA-5wxv-f8rx-4924 (GitHub Advisory).

The root cause is classified as CWE-120 (Buffer Copy without Checking Size of Input — 'Classic Buffer Overflow'), where the Scheduler component copies user-supplied input into a fixed-size buffer without validating that the input length is within bounds (GitHub Advisory). The attack vector is local, requiring no authentication or elevated privileges, and no user interaction beyond the attacker having access to the IDM Scheduler interface. Exploitation involves pasting a malicious string exceeding 5,000 bytes into the 'Open the following file when done' field, which overwrites adjacent memory and causes the application to crash. A public proof-of-concept exploit is referenced on Exploit-DB (EDB-ID 49083) (GitHub Advisory).

Successful exploitation results in a denial of service, causing the Internet Download Manager application to crash and become unavailable. The impact is limited to availability — there is no confidentiality or integrity impact, and the vulnerability does not affect subsequent systems beyond the local IDM process (GitHub Advisory). There is no evidence of lateral movement potential or data exposure risk associated with this vulnerability.

A proof-of-concept exploit is publicly available on Exploit-DB (EDB-ID 49083), referenced in the GitHub Advisory (GitHub Advisory). The EPSS score is approximately 0.012–0.015%, placing it in the 3rd percentile for exploitation likelihood within 30 days (GitHub Advisory). There is no evidence of active in-the-wild exploitation, no known threat actor attribution, and this CVE is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

1. Access the target system: Gain local access to a Windows system running Internet Download Manager version 6.38.12.
2. Open IDM Scheduler: Launch Internet Download Manager and navigate to the Scheduler component (typically accessible via the main menu or task scheduling interface).
3. Locate the vulnerable field: In the Scheduler dialog, find the 'Open the following file when done' input field.
4. Prepare oversized payload: Generate or copy a string exceeding 5,000 bytes (e.g., a repeated character string such as 'A' * 5001).
5. Paste malicious input: Paste the oversized string into the 'Open the following file when done' field.
6. Trigger crash: Confirm or save the scheduler entry; the application fails to validate input length, overflows the buffer, and crashes — resulting in a denial of service (GitHub Advisory).

• Process: Unexpected termination or crash of the IDMan.exe process on Windows systems running IDM 6.38.12.
• Logs: Windows Event Logs (Application log) may record an application error for IDMan.exe with a faulting module related to a memory access violation around the time of exploitation.
• File System: Presence of crash dump files (e.g., .dmp files) generated by Windows Error Reporting in %LOCALAPPDATA%\CrashDumps or similar directories following an IDM crash.

Users should update Internet Download Manager to a version newer than 6.38.12 that addresses this buffer overflow. A patch is referenced via GitHub Advisory GHSA-5wxv-f8rx-4924 (GitHub Advisory). As a workaround, restrict local access to systems running vulnerable IDM versions and avoid using the Scheduler's 'Open the following file when done' field with untrusted input. Implementing OS-level input validation or application sandboxing can further reduce risk.