# CVE-2025-59050: Greenshot — Insecure .NET deserialization via WM_COPYDATA enables local code execution

> A local attacker can execute arbitrary code in Greenshot by sending malicious serialized data via WM_COPYDATA, bypassing authorization checks.

- **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Sep 2025
- **Updated:** 16 Sep 2025
- **Also known as:** GHSA-8f7f-x7ww-xx5w

## What is CVE-2025-59050?

CVE-2025-59050 is a high-severity unsafe deserialization vulnerability in greenshot, published on 16 Sep 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Greenshot is an open source Windows screenshot utility. Greenshot 1.3.300 and earlier deserializes attacker-controlled data received in a WM_COPYDATA message using BinaryFormatter.Deserialize without prior validation or authentication, allowing a local process at the same integrity level to trigger arbitrary code execution inside the Greenshot process. The vulnerable logic resides in a WinForms WndProc handler for WM_COPYDATA (message 74) that copies the supplied bytes into a MemoryStream and invokes BinaryFormatter.Deserialize, and only afterward checks whether the specified channel is authorized. Because the authorization check occurs after deserialization, any gadget chain embedded in the serialized payload executes regardless of channel membership. A local attacker who can send WM_COPYDATA to the Greenshot main window can achieve in-process code execution, which may aid evasion of application control policies by running payloads within the trusted, signed Greenshot.exe process. This issue is fixed in version 1.3.301. No known workarounds exist.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2025-59050?

It affects 1 product.


Products: Getgreenshot Greenshot.

## How do I fix CVE-2025-59050?

No fix has been published for CVE-2025-59050 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-59050 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-59050 exists.

## Other vulnerabilities in greenshot

- [CVE-2026-22035](https://insights.sbomify.com/CVE-2026-22035/): Greenshot Vulnerable to OS Command Injection via ExternalCommand Plugin (high 7.8)
- [CVE-2023-34634](https://insights.sbomify.com/CVE-2023-34634/): Deserialization in n/a (high 7.8)
- [CVE-2026-25792](https://insights.sbomify.com/CVE-2026-25792/): Greenshot Vulnerable to OS Command Injection via ExternalCommand Plugin (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-59050 and fix it if it is affected.

What it is: CVE-2025-59050 is a high-severity unsafe deserialization vulnerability in greenshot, published on 16 Sep 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-59050 exists.

Affected product: greenshot. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-59050/ (Markdown: https://insights.sbomify.com/CVE-2025-59050/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-59050
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-59050
- OSV: https://osv.dev/vulnerability/CVE-2025-59050

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From sbomify Insights: https://insights.sbomify.com/CVE-2025-59050/
Summaries are generated and may contain mistakes; the official description above is the record.