Stack-Based Buffer Overflow in Notepad++ File Drop Handler leads to DoS
CVE-2026-5525 is fixed in Notepad++ on 1 platform by Notepad++ 8.9.4 (version 8.9.4), released April 26, 2026. It is not reported as exploited. Patch Radar priority: High.
A stack-based buffer overflow vulnerability exists in Notepad++ version 8.9.3 in the file drop handler component. When a user drags and drops a directory path of exactly 259 characters without a trailing backslash, the application appends a backslash and null terminator without proper bounds checking, resulting in a stack buffer overflow and application crash (STATUS_STACK_BUFFER_OVERRUN).
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Windows apps | |||
| Notepad++ | 8.9.4 | Notepad++ 8.9.4 | Apr 26, 2026 |
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