# CVE-2026-67300: FreeRDP before 3.29.0 Use-After-Free via async message proxy

> A malicious RDP server can trigger a use-after-free in FreeRDP clients with async updates enabled, leading to memory corruption or crashes.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Aug 2026
- **Updated:** 3 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-67300, GHSA-33gg-h66j-3697, GHSA-hp6g-g26j-5q54, UBUNTU-CVE-2026-67300

## What is CVE-2026-67300?

CVE-2026-67300 is a high-severity use after free vulnerability in FreeRDP, published on 1 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

FreeRDP before 3.29.0 contains client-side heap use-after-free vulnerabilities in the async update message proxy for RAIL WINDOW_STATE_ORDER and NOTIFY_ICON_STATE_ORDER when AsyncUpdate is enabled. When a malicious or compromised RDP server sends crafted update orders, the message proxy shallow-copies structures containing nested parser-owned pointers (e.g., titleInfo.string, windowRects, visibilityRects, icon buffers). The parser frees those nested buffers after the callback returns, so the queued async message later dispatches stale pointers, potentially causing memory corruption or a client crash.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-67300?


## How do I fix CVE-2026-67300?

Upgrade to a fixed version.

## Is CVE-2026-67300 being exploited?

There is no known exploitation of CVE-2026-67300 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-67300 and fix it if it is affected.

What it is: CVE-2026-67300 is a high-severity use after free vulnerability in FreeRDP, published on 1 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-67300 in the wild and no public exploit code.

Affected product: FreeRDP. 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-2026-67300/ (Markdown: https://insights.sbomify.com/CVE-2026-67300/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-67300
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-67300
- OSV: https://osv.dev/vulnerability/CVE-2026-67300

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-67300/
Summaries are generated and may contain mistakes; the official description above is the record.