CVE-2026-91961 FreeRDP before 3.31.0 Denial of Service via URBDRC
A malicious RDP server can crash the FreeRDP client by sending a specific control-transfer request with an invalid buffer size.
- 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-2026-91961?
CVE-2026-91961 is a high-severity denial of service vulnerability in Freerdp Freerdp, published on 15 Sep 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 before 3.31.0 contains a denial-of-service vulnerability in the URBDRC control-transfer request path that fails to validate OutputBufferSize before forwarding to the libusb backend. A malicious RDP server can send a control-transfer request with OutputBufferSize set to 65536, triggering a reachable assertion that terminates the client process.
Weakness: CWE-617
Which versions are affected by CVE-2026-91961?
It affects 1 product.
Products include Freerdp Freerdp.
How do I fix CVE-2026-91961?
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-2026-91961 being exploited?
There is no known exploitation of CVE-2026-91961 in the wild and no public exploit code.
Other vulnerabilities in Freerdp Freerdp
- CVE-2021-37594 Other in n/a
- CVE-2021-37595 Other in n/a
- CVE-2026-67305 FreeRDP Windows Client before 3.29.0 Heap Buffer Overflow via Cliprdr
- CVE-2026-66402 FreeRDP before 3.29.0 TLS Certificate Identity Validation Bypass
- CVE-2026-67289 FreeRDP before 3.29.0 HTTP Proxy Request Injection via Redirection
Sources
Also known as DEBIAN-CVE-2026-91961, GHSA-fqjp-p646-qwhr, GHSA-w9qg-g24r-77f6, UBUNTU-CVE-2026-91961.