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.
- 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
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
Which versions are affected by CVE-2026-109240?
How do I fix CVE-2026-109240?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-109240 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-109240 exists.
Sources
Also known as DEBIAN-CVE-2026-109240, GHSA-9qqc-m43j-g4r2, GHSA-9xp7-4872-49v6, UBUNTU-CVE-2026-109240.