# CVE-2026-109240: FreeRDP 3.11.0 before 3.32.1 Reachable Assertion DoS via urb_isoch_transfer

> A malicious RDP server can crash FreeRDP clients by sending oversized buffer values, causing a reachable assertion failure.

- **Severity:** Low 2.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 12 Oct 2026
- **Updated:** 13 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-109240, GHSA-9qqc-m43j-g4r2, GHSA-9xp7-4872-49v6, UBUNTU-CVE-2026-109240

## What is CVE-2026-109240?

CVE-2026-109240 is a low-severity denial of service vulnerability in FreeRDP, published on 12 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

FreeRDP 3.11.0 before 3.32.1 contains a reachable assertion vulnerability in urb_isoch_transfer that allows malicious RDP servers to crash clients by sending unvalidated OutputBufferSize values. Attackers can send a TS_URB_ISOCH_TRANSFER IN-direction request with OutputBufferSize above INT32_MAX over URBDRC, triggering an assertion in libusb_udev_isoch_transfer that terminates the client.

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2026-109240?


## How do I fix CVE-2026-109240?

Upgrade to a fixed version.

## Is CVE-2026-109240 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-109240 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-109240 and fix it if it is affected.

What it is: CVE-2026-109240 is a low-severity denial of service vulnerability in FreeRDP, published on 12 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-109240 exists.

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-2026-109240/ (Markdown: https://insights.sbomify.com/CVE-2026-109240/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-109240
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-109240
- OSV: https://osv.dev/vulnerability/CVE-2026-109240

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-109240/
Summaries are generated and may contain mistakes; the official description above is the record.