Local code execution via pre-authorization WM_COPYDATA deserialization
Published Sep 16, 2025 · Updated Sep 16, 2025
Insecure deserialization in Greenshot 1.3.300 and earlier allows local users to execute arbitrary code through a crafted WM_COPYDATA message. The WinForms WndProc handler copies message bytes into a MemoryStream and calls BinaryFormatter.Deserialize before checking whether the embedded channel is authorized. A process at the same integrity level must reach the Greenshot main window; successful exploitation runs payloads inside the trusted, signed Greenshot.exe process.
Summary
What happened
Insecure deserialization in Greenshot 1.3.300 and earlier allows local users to execute arbitrary code through a crafted WM_COPYDATA message. The WinForms WndProc handler copies message bytes into a MemoryStream and calls BinaryFormatter.Deserialize before checking whether the embedded channel is authorized. A process at the same integrity level must reach the Greenshot main window; successful exploitation runs payloads inside the trusted, signed Greenshot.exe process.
The record
- CVE
- CVE-2025-59050
- Published
- Sep 16, 2025
- Updated
- Sep 16, 2025
- Vendor
- Greenshot
- Product
- Greenshot
- Classifications
- CWE-502, T1055
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 16, 2025CVE publishedPublication date reported by the CVE source.
- Sep 16, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 1.3.301
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- WM_COPYDATA BinaryFormatter proof-of-concept demonstrationproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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